TODAY, IF THE father of our country could escort a few out-of-town visitors up from his estate at Mount Vernon to Great Falls, Virginia -- where he once built a canal -- he would certainly take the George Washington Memorial Parkway most of the way.

Not just because it's named after him -- though this would certainly tend to impress out-of-town visitors.

And not just because it would take him through his old port of Alexandria -- where the stoplights still keep the average traffic speed down to a comfy, colonial-era 5 miles per hour (or so it seems). Nor just because it runs past the tidewater town that nowadays bears his name, and then climbs on up into the Potomac palisades, and thereafter connects to the Beltway.

No. These are good reasons, but the chief reason that Washington -- and we modern-day Washingtonians -- would take the George Washington Memorial Parkway is a simple one:

It affords the best, most perspective-filled four-wheeled introduction to one of the prettiest nation's capitals around.

That would be Washington, D.C. It's over there -- the thing with the obelisk.

In addition, if you park those four wheels somewhere, almost anywhere, and get out of the car, you will find that this road is not called a parkway for nothing.

It was, in fact, the first federal parkway -- although, with an eye toward funding, its creators christened its original section (from Memorial Bridge to Mount Vernon) the Mount Vernon Memorial Highway, lest Congress get the idea somebody was planning to lay down more than a road with the taxpayers' money.

Of course, they did build more than a road -- except maybe between Spout Run and the Roosevelt Bridge during any rush hour, when, as any taxpaying commuter and several latter-day congressmen will testify, it is significantly less than a roa.

Well, nevertheless: Along its 32 river-hugging miles on the Virginia side, between Mount Vernon and the Beltway, and along an additional 10 miles from this side of Great Falls, Maryland to the Chain Bridge, the parkway is thick with non-commuter destinations -- for cyclists, hikers, joggers, picnickers, fishermen, naturalists, boaters, birdwatchers, plane-watchers, pleasure-drivers, strollers, sailors, history buffs and even those of us who missed the Memorial Bridge exit and are now hopelessly lost.

The GW Parkway is not a bad highway on which to get lost, accidentally or otherwise. And it is also the best single highway on which to catch some lasting glimpses of Washington: The man, the monument and the metropolitan area.

It is with these two purposes -- getting deliberately and pleasantly lost, and getting an introduction (even if you've been working in D.C. for years, or have spent half your life merging at Spout Run) that we make the following mid-autumn weekend daytrip. FIRST STOP: MOUNT VERNON

Because most stops along the parkway are easiest to reach from the northbound lanes, and because both Washington's founding-father reputation and his namesake highway start here, so will we. At Mount Vernon, the southern terminus of the parkway, you'll find a good part (about 500 acres) of the original Washington estate -- including the unbeatable back- patio Potomac view, the gardens, the outbuildings and the grand hilltop house itself. (The estate, owned and maintained since the 1850s by the Mount Vernon Ladies' Association of the Union, in Washington's day stretched most of the way to what is now Alexandria -- about day's work for a horse, to the property line and back.)

Today, it's a 15-minute drive from Old Town, and it'll cost you $4 to see the place ($2 if you're 6 to 11, $3.50 if you're 62 or older). Parking is free and -- 50 years after the lots were designed, believe it or not -- easy. If you came just to use the rest roms, or collapse beside your 10-speed on the wide, elm- dotted oval out front (the Mount Vernon Bike Trail starts here), that's also on the house.

At this particular moment, the oval is littered with break- taking bicyclists. There are the dozen folks from Keller & Heckman, on an office outing. There's David King, who lives in D.C. and hits the trail three times a week (and has memorized the water-fountain locations), chatting on the grass with Michelle Kochis of Springfield, who used to jog the trail when she lived in Alexandria. And there's Wendy Steggerda, who moved to Washington from Boston a few weeks ago; after an 18-mile trip from Arlington this morning, she's inclined to think the parkway route beats anything along, say, Storrow Drive. "This is so much nicer," she says.

For perspective on the car trek, however, don't take the parkway itself down to Mount Vernon, even though it's the simplest route. Instead, consider arriving via the patchwork- pavement and plastic-sign sprawl of U.S. 1. This'll give you a good idea of what might've happened along the riverside route you're about to take, had the Agriculture Department's Bureau of Public Roads not been authorized in 1928 to build a commemorative, scenic highway from the Memorial Bridge to Washington's historic home.

The 15-mile Mount Vernon Memorial Highway, opened in January 1932, was to be the first quarter of what some envisioned as a vast circular parkway -- ringing the Potomac from Great Falls to Mount Vernon on the Virginia side, and from Great Falls to Fort Washington on the Maryland side. This plan, for a variety of reasons (most of them privately owned, if you catch my drift), never came to be. But the parkway was extended from Memorial Bridge north to Spout Run in the late 1940s, to the CIA headquarters above Chain Bridge in the late '50s, and to the Capital Beltway on both sides of the river in the mid '60s.

But, we digress -- a common hazard on this particular road. arly on a nice fall day. ONWARD AND UPRIVER

Headed north from Mount Vernon on this nice day, the first break in the oaks, elms, cedars, willows and curving concrete you come to is the Riverside Picnic Area. In less leafy months, you can look back downriver from here and see the Mount Vernon mansion; at the moment, you can see just the estate's wharf, and the probably-soon-to-be-developed wilderness on the Maryland shore across the way.

The small parking lot here is almost full, and the half-dozen picnic tables are all taken. After watching a picnicker's Dalmatian shoot out of the shadows, yelping, after a bicyclist -- only to be shouted into submission by both the bicyclist and the picnicker -- we move on. FORT HUNT

Between Riverside and Fort Hunt are a couple of small parking areas, for picnicking or bike-path access, plus the Cedar Knoll Inn, a privately owned German-American restaurant with an interesting history (pick up a pamphlet in the foyer) and probably the best dining-room view of the Mount Vernon Highway and the river beyond.

At Fort Hunt Park, on the site of a fort built to guard the river approach to Washington in 1898, are now 156 acres of picnic areas, National Park Service stables, playing fields and the concrete ruins of two Spanish American War gun emplacements. One of them -- a spooky, low-slung mass of dark doorways and exterior stairs which formerly held three eight-inch breech-loading guns -- this past summer served a more cheerful military purpose: It was the bandstand for a series of Saturday afternoon Army Band concerts. (The series, "Mount Vernon Battery Music," was a success in under-populated Fort Hunt, and Park Service interpretive specialist Corky Mayo says it'll be back next summer.)

Meanwhile, the place is relatively deserted, for a Saturday. There's time to stroll past an instructor teaching a group of kids some sort of martial arts technique that involves big sticks and lots of yelling. Or to have a brief conversation with one of the Park Service's beautiful horses, or to watch the occasional Serious Bicyclist (helmet, special shoes, no waist) whiz by, on a popular bike-trail detour.

Let's get out of here before we get some exercise. FORT WASHINGTON OVERLOOK

There's a small parking area just past the northbound entrance to Fort Hunt; this is the overlook. Fort Washington, which you could actually tour if you were over there in Maryland, looks from here like something out of medieval Spain -- a squat stone fortress set forever into a hill, which served the same river-defense purpose as Fort Hunt. Except Fort Washington was meant to be seen. COLLINGWOOD PICNIC AREA AND BEYOND

The small Collingwood Picnic Area gets mentioned because it is shadier (thank the big old cedars), prettier and always seems less crowded than Riverside or the other areas nearby, and because there is no bike path here -- the path crosses under the parkway to the other side at Fort Hunt. So next time, consider bringing the Dalmatian here.

From here north, including the road construction area (the parkway is being resurfaced and re-medianed, eventually to Mount Vernon) between Morningside Lane and the Alexandria city limits, the river views and otherwise isolated feeling are diminished by the proximity, on both sides of the parkway, of private homes. Also along this stretch are the American Horticultural Society headquarters and the Collingwood Museum and Library of Americanism. It is as you're about to visit the modest, reverent (and free) exhibits of the latter that you almost bump into a man dressed entirely in a colonial uniform of some kind. He smiles, however, and appears to be armed only with a 35-mm camera. BELLE HAVEN MARINA/DYKE MARSH

At the marina here, behind all the construction cones, dirt- movers and temporarily bombed-out roadbed, you will find a popular boat-launching ramp, and an adjacent large picnic area between the bike trail and the river. Today, you will also find Mark Dorman, a Crystal City dweller and Old Town Art League member whose easel is set up to help him capture, in oil, the seasonal color-burst of a red oak at the river's edge. "I'm just learning," he says, "but this is a very good place for this. You can paint the trees here, or go over to the marina and paint the boats. And I also do photography, so it's good for that. And it's just nice to have company, and feedback about your work. A lot of people stop and look."

From the river's edge here, the Wilson bridge is visible, though not audible, as is the Jones Point Lighthouse -- surrounded by about 50 acres of undeveloped land on which a privately owned Harborplace-type development is planned. None of the aforementioned, in any case, makes it to Dorman's canvas. Today, he's just into the tree.

Roughly 100 yards south of the marina -- and you have to walk, unless you're on a bike -- is the gravel road hat leads to the 240-acre Dyke Marsh wildlife sanctuary, nesting place for heron, mallards, egrets, blackbirds, woodpeckers and others, and a stopping-off point for as many as 250 other species. ALEXANDRIA

Fifty years ago, there were a few Mount Vernon Memorial Highway planners who considered skirting Old Town Alexandria. But no, this just wouldn't do -- considering the town's historic character, its George Washington connection and its etched-in-brick promise to keep its architecture, old and new, always looking . . . well, old. Thus the Mount Vernon Memorial Highway becomes Washington Street for two miles, and the timing of Washington Street's traffic lights gives you plenty of time to consider stopping at the Old Club (George Washington actually did eat here, often) or Christ Church, or Gadsby's Tavern or any of the scores of shops and restaurants of this genteel, dangerously adorable little hamlet.

In any case: On your way north and out of town, at the traffic light at Slater's Lane -- which is unique in that it apparently never turns green until every car within sight has come to a complete stop -- look up ahead. There's your first glimpse of the Washington Monument. While you're waiting for the light to change, there's a good chance you'll see a flight departing National Airport, crossing diagonally in front of the monument. This is kind of an intoxicating sight -- unless, of course, that was your flight. WASHINGTON SAILING MARINA/DAINGERFIELD ISLAND

Yes. You will notice a distinct change in the parkway's character from Alexandria north. The views are no less impressive -- they are, in fact, more impressive, if you aren't looking so much for trees and hills as for views of that monumental, highly picturesque city across the water. But your roadmates, most of whom automatically do 20 mph over the 40 mph limit hereabouts, are less interested in sightseeing -- and less forgiving of those of us who aren't headed for a power lunch this particular afternoon.

So, we arrive at Daingerfield Island, and the Washington Sailing Marina, probably sooner than we thought. If it's a sunny weekend afternoon through Thanksgiving, you're most likely going to have to park in the overflow lot closer to the picnic areas, playing fields and hiking-birdwatching trails of Daingerfield Island proper than the restaurant, rest rooms and snack bar/cafe of the marina itself. Fine. If your money's in one of the marina's slips, you're already used to walking a long way to wash your face. And if you're headed for the restaurant -- Potowmack Landing, apparently named for the dining-room view, which is of planes landing over the Potomac -- you need not hurry unless there are tourbuses parked nearby. WASHINGTON NATIONAL AIRPORT

You don't want to go in here unless you have to, or unless somebody told you that this was the only way to make money as a cab driver. Either way it's not on the tour, and we're not responsible. If you're on a bike and you come to a sign here that says "Stop," for God's sake -- stop. GRAVELLY POINT

An interesting place. On the surface -- and especially on the weekend -- this seems to be just a popular point to launch one's boat into Roaches Run, and thus the Potomac. Otherwise, there's nothing here. Maybe one picnic table. And Washington National Airport, a bottlecap's throw across Roaches Run.

But look at all the people: Tons of them, many of them families with young children, sitting languidly on the grass, watching planes take off from Runway 1836 -- National's main runway, the north end of which is only about 200 yards away. This means you don't just watch planes take off when you're at Gravelly Point. You hear them take off. You feel them, right down to your coccyx. It's an acquired fascination, but there's a surprising amount of repeat business.

Charlie and Kim Maneval, a young Alexandria couple, are sitting on the grass, near the parking lot. He's reading; she's doing needlepoint; the sky, meanwhile, is falling. He's been here before, she says, but this is her first time. They look very much at home. "I like to watch the planes," says Charlie. "It's not like we come here all the time."

You've always wondered why people come to Gravelly Point. So, this is it: They come to hear the planes take off.

"We don't come to hear them take off," Charlie Maneval says, giggling. "We come to see them take off."

Ah. A man is talking on the outdoor pay phone nearby. An American Airlines DC-10 is nearing the lift-off point over on Runway 1836, meanwhile, and the guy knows what's coming -- so he starts talking fast, trying to fit everything in before the roar gets so loud you can't hear anything and hold on wait a minute aw jeez . . . .

The plane passes directly overhead; you can see the landing gear retract. The guy on the phone smiles at a sympathetic onlooker as the very air around us warps, shudders and rips into a million pieces. And then he shrugs, and holds the receiver to his chest until the roar subsides. On the riverbank, a toddler waves.

Bye-bye! COLUMBIA ISLAND MARINA/LBJ MEMORIAL GROVE

There are slips, a boat ramp, a concession and rest rooms here, but you can only reach the parking lot by car if you're southbound. Adjacent to the marina parking lot is the Lyndon Baines Johnson Memorial Grove, which we northbounders-in- the-know can reach by taking I-395 south (the next interchange north on the parkway) and exiting immediately onto Boundary Channel Drive. You'll come to a parking lot here, right alongside the world-dominating Pentagon lot, and you can cross the pedestrian bridge over the channel to reach both the grove and the marina.

Aside from the LBJ Grove's obviously cared-for plantings -- perennials in the spring and summer; wildflowers later; rhododendron, azalea and dogwood all over the place -- you really should visit the central, semi-secret courtyard of his small grove. Here, you'll find a tall slab of pink Texas granite, framed by cherry laurel, white pine, ivy, rhododendron and cotoneaster -- and, to the east, across the parkway, one of the most wonderful wide-angle views of the capital city that you'll see anywhere. Picture, from left: the Memorial Bridge, the Lincoln Memorial, the Tidal Basin's cherry trees and Jefferson Memorial, and the Capitol dome. The grove itself is littered with bicyclists and joggers (this is a popular base for cars with bike racks), but not a soul shows up in the courtyard while you're there. NAVY AND MARINE CORPS MEMORIAL

Northbound again. This is the striking waves-and-gulls sculpture right on the river, designed in 1922 by Ernesto Bagni del Piatta to memorialize the fighting men of the sea. It's almost directly opposite the LBJ Grove (and both the grove and the monument are officially part of Ladybird Johnson Park). There's a tiny, dangerous-when-full (and it's always full on weekends) parking lot just past the sculpture. At the moment, a young girl is posed on top of the sculpture, sort of curled inside one of the waves, while her mom -- and dad, and grandmom, and big brother, three Japanese tourists and much of the Mormon Tabernacle Choir -- all take pictures. MEMORIAL BRIDGE

The official northern terminus of the Mount Vernon Memorial Highway portion of the parkway, and also the place to exit if you aim to see Arlington Cemetery, the U.S. Marine Corps (a.k.a. Iwo Jima) Memorial, the Netherlands Carillon or, at the D.C. end of Memorial Avenue, the Mall and all.

The bike trail also ends here, unless you cross the bridge into Washington. The Park Service is planning a pedestrian/bicyclist bridge from Roosevelt Island to Rosslyn Circle, to lead the Mount Vernon Bike Trail directly -- and much less dangerously -- into the Washington & Old Dominion Trail (along I-66), thus connecting Mount Vernon with Purcellville and the Shenandoah.

In any case, the granite-veneer Memorial Bridge was opened in 1932, at the same time as the Mount Vernon Memorial Highway, but it cost twice as much ($15 million) to build. THEODORE ROOSEVELT ISLAND

About a mile north of the Memorial Bridge is Theodore Roosevelt Island, 88 acres of relatively undisturbed nature -- marsh, swamp and upland forest -- maintained in tribute to a president who frequently sought refuge in the wild. There's a 17-foot bronze statue of TR near the northern center of the island, which is otherwise adorned with a simple, frequently sun- sheltered trail.

If the main parking lot is full (and sure enough, it is), there's another one just past it -- but this one's awfully treacherous to enter and exit, especially if the guy behind you is trying to read the fine print on your bumper sticker.

At the north end of the overflow lot, you'll see a sign marking the start of the Potomac Heritage Trail, a recently opened rough hiking trail along the Virginia bank and bluffs of the Potomac, up to Chain Bridge. (You can take Pimmit Run from here back up to a path along the wooded edge of the parkway, which brings you to Turkey Run Park, where you can then descend to the river again and follow the trail to Fairfax County's Dranesville Park, just upriver from the Beltway.) KEY BRIDGE, SPOUT RUN AND SO ON

The parkway's personality changes again here, just past the ill-conceived, accident-g of the parkway, the Key Bridge ramps and Spout Run. You're about to leave the coastal plain for the piedmont: Hence the roadbed begins a slow climb upward, straight at first and then gently curving. The speed limit signs now say 50 mph (which means everyone now does at least 60), and the riverbed drops off sharply until it's close to 60 feet down and out of sight. What you see across the river are the opposing palisades -- Georgetown University, and the thickly wooded, overpriced hills of upper Northwest. THE OVERLOOKS

If you're coming the other way, from the Beltway south, about three miles above Spout Run is where the roadbed's architects give you your first glimpse of the Washington Monument and the city around it -- but you can't stop anywhere if you're southbound. Lucky for us we're northbound, where there are two consecutive overlooks, well marked.

At the first, there's a 35-ish fellow in a beat-up Ford who says he appreciates "the parkway as a parkway, here along the river. I think it's a legitimate use. A lot of people with visitors can take them on this road, and it's real quick way of getting a feel for the surroundings." He says he's lived in the area three years, but this is the first time he's ever stopped at the overlook -- any overlook. "I just saw the sign and thought what the heck," he says.

At the first overlook, you can see the famous Monument downriver, behind Georgetown U., and the towers of Rosslyn to the far right. Straight down and across is Fletcher's Boat House, with a sprinkling of calm-water fishermen atop the seasonally diminished river.

At the second overlook, above Donaldson Run, the view is of the river and the red-gold-brown foliage above it; you can hardly see Georgetown, let alone the city. You might as well be on Skyline Drive. Which is kind of nice, because you're only about six miles from M Street. FORT MARCY

Three miles north are the remains of an earthen fort that Union troops built in 1861 to guard the Virginia approach to Chain Bridge. There several picnic tables, a cannon inexplicably pointed at the parking lot, and a handful of terse plaques. Even on weekends, the place is often deserted -- if you park in the small, secluded lot and walk to the edge of the park, you're looking at the traffic on Chain Bridge Road. Now you know why, like the one McLean couple you meet on the way in, you've passed the Fort Marcy exit sign for eight years and never stopped -- thre's really not much to do here.

Although it does make for a nice place to take a walk with a friend. No doubt a popular trysting spot, even if it does close at dark. THE CIA AND PARKWAY HEADQUARTERS

There are no tours of the CIA. Sorry. You can turn around here, sir.

If you exit at Parkway Headquarters just beyond, however, you may run into Parkway Superintendent John Byrne, or any number of the similarly helpful people who actually seem to enjoy running this long, narrow conservation-and-commuting wonder (it's the 12th largest National Park Service unit, in budget and staff). Someone may tell you that the park consists of 120 "lane miles," 30 miles of Potomac shoreline, and an average daily traffic of 90,000 carloads. But there are no tours here, either. Keep going. TURKEY RUN PARK

If you were looking for the Claude Moore Colonial Farm at Turkey Run, you should've exited at Route 123, just past Fort Marcy and about five miles south of the Parkway's Turkey Run exit. Unlike Fort Marcy, the Turkey Run Park here has access to and terrific views of the river (particularly in fall and winter), many picnic areas, rest rooms and a recently cleared wide path down to the Potomac shore -- where you can fish, spot birds or pick up the Heritage Trail to the Beltway. BEYOND THE BELTWAY: GREAT FALLS

In Virginia, the parkway ends at the Beltway. And Virginia's Great Falls Park, which is administered by the same people who administer the parkway but isn't on the parkway, is something you should consider visiting -- particularly if you haven't yet seen the falls, or if you don't mind a 20-minute detour south on I-495 and west on winding Route 193. At the park -- where the river drops about 80 feet in less than a mile, and where George Washington once brought to fruition a short-lived, now partially restored engineering feat called the Potowmack Canal -- you will find many picnickers, many picture-takers, a food concession, a visitor center (see the diorama of the canal) and one of the nicest walks anywhere along the river, down to the totally uncivilized Mather Gorge at the base of Great Falls.

The river is running low at the moment, but the falls are still impressive. Even more impressive is the sign you'll encounter at Overlook No. 2, a concrete platform towering over the rushing water below. Right there at eye level on the sign is a black painted stripe. Next to the stripe it says: "High water mark, 1972. Hurricane Agnes." AND INTO MARYLAND

From the Virginia parkway, take the Beltway north to just over the Cabin John Bridge (a short passage which the current bridge work can turn into an enduring pain) and turn right. You're now on the Maryland portion of the George Washington Memorial Parkway. Officially, it stretches from MacArthur Boulevard, just upriver from the popular big-group picnic area at Carderock, then parallels MacArthur and the river -- and provides access to half-a-dozen locks along the C&O Canal towpath -- down to the Chain Bridge, where it becomes Canal Road.

Its chief attractions -- other than the towpath itself, and the patchwork, never-quite-finished pattern of merges from one lane to two and back -- are the amusement-park-turned-arts- center at Glen Echo, and the Clara Barton House nearby. Both are reached by exiting at MacArthur Boulevard, halfway between Chain Bridge and the Beltway.

The restored and appropriately furnished Clara Barton House, a 41-room building that was the headquarters of the American Red Cross and the home of its founder from 1897 to 1904, makes for a particularly engrossing peek into the life of a woman who turned her naturally generous spirit into a kind- hearted empire. THE GEORGE WASHINGTON MEMORIAL PARKWAY -- For information about hours, boat and bike access, picnic permits, etc.: 285-2600.