WEEKEND travelers in the Washington area should rejoice. The problem is not deciding whether to go, it's where to go this weekend. Nearby are beaches and mountains, old historic towns and modern amusement parks, museums and monuments, fields of battle and vast stretches of nature's marvels.

Here are enough of Weekend's favorite weekend getaways to keep you and your Visa card busy for a year:

THE BRANDYWINE VALLEY -- The Brandywine River Valley, located in Delaware and Pennsylvania just two hours north of the Beltway, is rich in history and art. The Du Ponts made their fortune here and left behind two grand mansions -- Winterthur and Nemours -- that are open for tours. The 350 acres of flowers, trees, topiary gardens and fountains (plus four acres indoors) at Longwood Gardens ares the work of one of the Du Ponts and are modeled after the royal gardens of Europe. The Brandywine River Museum displays the works of three generations of Wyeths; the Chaddsford Winery holds festivals almost every weekend; and quaint inns offer comfortable lodging and fine food. To get there, take I-95 north to Rte. 52 to Wilmington, and on into the rolling country of the Brandywine. It's 110 miles north of Washington. For more information, call or write the Greater Wilmington Convention and Visitors Bureau, Box 111, Wilmington DE 19899. 302/652-4088.

THE BEACHES -- No matter what season you visit, the Atlantic beaches promise a relaxing retreat. Most Washingtonians' shore destinations are 2 1/2 to 4 hours away. Here is a quick primer: Rehoboth and Bethany are smaller than nearby Ocean City, Maryland, and these Delaware towns are generally quieter. There are fewer nightspots, less traffic, better restaurants and more galleries and boutiques. Take U.S. 50 east across the Bay Bridge and follow the signs to the Delaware beaches. For more information: Lewes, Rehoboth and Dewey Beach: 800/441-1329. Bethany: 302/539-8011. Ocean City (follow U.S. 50 all the way east) is a bigger, bustling strip city. During the summer, the action seems endless. There's less to do in the winter, but enough to occupy a weekend. 301/289-8559. Virginia Beach is farther away than the Maryland and Delaware spots, but this city is more of a year-round vacation spot. If the weather turns bad, the many attractions in nearby Norfolk and Hampton can keep you busy. Take I-95 south, then I-64 east to the shore. 800/446-8038.

WINE COUNTRY -- There are more than 40 operating wineries in Virginia and Maryland. Most of them are open for tours, tastings and seasonal festivals. For a weekend getaway, try the numerous wineries around Charlottesville or in the Shenandoah Valley. For a brochure listing the Virginia wineries and a schedule of their festivals, write the Wine Marketing Program, Department of Agriculture and Consumer Services, Division of Markets, P.O. Box 1163, Richmond, VA 23209. In Maryland, write the Department of Agriculture, Marketing Services, 50 Harry S Truman Parkway, Annapolis, MD 21401.

AMUSEMENT PARKS -- The area is blessed with them. In Virginia, there's King's Dominion, two hours away on I-95 north of Richmond. Busch Gardens/The Old Country is three hours away in Williamsburg. Nearer Washington, Wild World and its playland of water slides is in Largo. Three hours' drive north, in Hershey, Pennsylvania, you'll find Hershey Park, a smaller, older amusement park (with Chocolate World next door) and on U.S. 1 north of Philadelphia, Sesame Place is a play park for fans of Big Bird and his friends.

AWAY AFLOAT -- Sail yourself or sit back while someone does the hard work for you. Either way, a boat might be just the escape for you. There are two ways to do it: Learn to sail and handle a boat and then charter one yourself; or just charter with a captain and let him do the work. You can get a list of the yacht charter agencies and sailing schools in the Annapolis area from the Anne Arundel Chamber of Commerce, 301/268-0434.

DRIVING TOURS -- If you don't know where you want to go, but want a drive that has antiques, scenery, quaint towns, fine restaurants for dinner and a nice inn for the night, here are some proven routes:

Skyline Drive and the Shenandoah Valley. Pick up the Skyline Drive at Front Royal (60 miles west on I-66) and head south. The drive will be slow, and the stops at the lookouts many, so don't plan to do it all in one weekend. Try getting off near Waynesboro and heading west to Staunton. After overnighting there, come back home by taking Route 11 north and enjoy the small towns and views of the west side of the Shenandoah Mountains. Shenandoah Valley Travel Association: 703/740-3132.

Chestertown. The busiest port on the Eastern Shore 200 years ago, it's now a pleasant small college town with brick sidewalks, intriguing shops and fine 18th-century houses and gardens of wealthy merchants still lining Water Street, parallel to the Chester River. You can pick up a free walking tour and map weekdays from the Chamber of Commerce in the Town Office Building at 118 N. Cross St. (weekends you'll find them in the information box behind the Chestertown Newstand on High Street). Take U.S. 50 across the Bay Bridge to U.S. 301 north and watch for the signs. 301/778-0416.

St. Michaels/Oxford/Easton. These three small towns on Maryland's Eastern Shore are wonderful places to visit in the fall when the waterfowl are visiting. Easton, the largest of the three, has its annual Waterfowl Festival in early November and the nearby Blackwater National Wildlife Refuge is the place to look at the geese. St. Michaels and Oxford are Revolutionary Era ports with inns, boutiques, restaurants and scenery.

Frederick. This town set on the edge of the Catoctin mountains is filled with wonderful old homes, quality antique shops and fine restaurants. Nearby Cunningham Falls State Park and Catoctin Mountain Park on U.S. 15 are places for campers, hikers and seekers of a calmer, greener world.

Harpers Ferry and the nearby towns of Shepherdstown and Charlestown are historic towns with a number of quaint inns and hotels, shops and restaurants. 304/725-2055.

INN ADVENTURES -- Country inns seem to be turning up in every small town and crossroads. Some, however, offer more than a bucolic view and a country breakfast. Murder mysteries, for example. The Harry Packer Mansion in Jim Thorpe, Pennsylvania, has a murder every weekend, September to May. 717/325-8566. The Society Hill Hotels in Baltimore have a mystery weekend that leads the detectives throughout the city. Three numbers to call (all area code 301): 837-3630, 752-7722 and 235-8600. Guesthouses and Boxwood Tours also has mystery weekends at homes in Pennsylvania's Brandywine country. 215/692-4575. The same group also offers weekends of elegance in some of thegrander country manors. Other theme weekends -- music, drama, Halloween and comedy -- can be arranged at Dearmont Hall in White Post, Virginia (703/837-1397) and the River House in Boyce, Virginia (703/837-1476).

BALTIMORE -- The Colts are history (and the old Orioles a memory), but this historic town is experiencing a rebirth down in its harbor areas. Harborplace and the neighboring Maryland Science Center and the National Aquarium entertain thousands daily. Don't overlook Bolton Hill, location of some of the city's finest Victorian mansions; Fell's Point, a working port whose waterfront streets are being revitalized by new shops and restaurants; Lexington Market, center of gastronomy; and the fine museums, particularly the Baltimore Museum of Art and the Walters Art Gallery. 301/837-INFO.

RICHMOND -- Founded in 1737 by William Byrd II, Richmond is a modern city that still bears traces of its historic past. The Capitol, designed in part by Thomas Jefferson, and the meandering paths of nearby Capitol Square are worth a visit. The Shockoe Slip Historic District, on East Main Street toward the James River, is an old area that is bustling with new shops and attractions. Franklin Street has a number of pre-Civil War buildings. And visit the Virginia Museum of Fine Arts, the Valentine Museum (regional history) and the Museum of the Confederacy. For more information: 804/358-5511.

WILLIAMSBURG -- After some 60 years of restorations, more than 80 original buildings have been restored in this town that was the second capital of Virginia. The gardens, taverns, workshops, museums and historic government buildings can keep you busy for a month of weekends. Nearby, Busch Gardens/The Old Country and its entertainment and rides will delight the younger members of the family. It's open April through October. 804/253-0192.

ANNAPOLIS -- Boats and boutiques. The capital of Maryland is becoming the Yup, Fern and Brass capital of the region. But the upscale shops and trendy restaurants cannot hide the crabbers and working sailors who abound here. Visit the Naval Academy while here. The museum and grounds are beautiful. Annapolis also has a number of fine inns. Call Historic Inns of Annapolis at 301/263-2641.

DOWN THE SLOPES -- Ski resorts, believe it or not, can be found in West Virginia and Virginia, western Maryland, and lower Pennsylvania. The best skiing, however, probably will not be found until after New Year's. For a quick run down on the slopes, visit your local ski shop, which might also have some flyers on discount packages. (You might also look for Weekend's annual Ski Issue, coming this November 27, plus our weekly Ski Reports throughout the season.)

LAST, RESORTS -- Okay, so what you really want is a place with great food, some indoor and outdoor sports activities, a health spa to soak and massage those aches away, with enough nightlife to keep you awake long enough to have a nightcap. Luckily, there are three of Mobil's five-star resorts in the region, and two that win four-star ratings. All offer superb food and accommodations, year-round sports activities, special theme weekends and nightlife. Rates run from about $100 a night (room only) to $100 and up per person per night, breakfast and dinner included. It isn't cheap, but it can be wonderful. The five-star resorts are: The Greenbrier, White Sulphur Springs, West Virginia, 304/536-1110 or 800/624-6070. The Homestead, Hot Springs, Virginia, 800/468-7747. The Williamsburg Inn, Williamsburg. 800/HISTORY. All offer golf, pools, dancing, fine food and other attractions. The four-star resorts are: The Tides Inn, Irvington, Virginia. 800/TIDESIN and the Boars Head Inn, Charlottesville, Virginia. 804/296-2181.

FOR MORE INFORMATION . . .

For more information about inns and area attractions, the following books will help. Your library will have most of them. Travel Books Unlimited of Bethesda should have all of them.

AWAY FOR THE WEEKEND: WASHINGTON, D.C. -- 52 getaways in Delaware, Maryland, Virginia, West Virginia, Pennsylvania and New Jersey. Eleanor Berman. Crown, $11.95.

ADVENTURE VACATIONS IN FIVE MID-ATLANTIC STATES -- by Carolyn Mulford and Betty C. Ford. EPM Publishers. $9.95.

JIM YENCKEL'S GREAT GETAWAY GUIDE -- by James T. Yenckel. The second edition is out soon. Andrik Associates.