SAN SIMEON is like the Prado. It's exhausting," said the driver of the car which took us up the famed Pacific Coast Highway from Los Angeles to San Francisco. "The plate is too full."

None of the literature, none of the pictures, no one's eyewitness account prepares you for the enormity of the Hearst Castle atop a hill over looking the Pacific Ocean on three sides and a gentle mountain range on the other. Located in the little town of San Simeon, the castle is San Simeon. And San Simeon is hyperbole. There are so many treasures covering every inch of the floors, walls and ceilings that a Gobelin tapestry is a mere afterthought on a guided tour.

On the other hand, no one really prepares you for the Pacific Coast Highway, sometimes known as Route 1, sometimes as 101, but always as El Camino Real. Of course they tell you how magnificent the scenery is, how narrow the road, how sheer the cliffs, but little if anything about the manmade attractions along the way, even the historic missions. Or about the people.

Take Solvang, for example, less than 50 miles north of Santa Barbara. Not until we were in shouting distance did we even know about this "authentic replication" of a Danish village, complete with a benevolent stone carving of Hans Christian Andersen. Within minutes of the coastal highway (which is inland at this point), Solvang is just a jog down the road from Pea Soup Anderson's motel and restaurant in Buellton. Anderson's takes its name from the pea soup which brought it fame. The same pea soup is still served, but isn't famous.

Solvang was founded as the site of a Danish folk school 67 years ago by a group of Danish educators. The Danish architecture was an afterthought, dreamed up in 1947. Today Solvang is Instant Denmark.

Now everything that shows has to have heavy beams implanted in brick or masonry walls, tile, simulated thatch or copper roofs, dormers, stained glass windows and cobblestone sidewalks. According to a tourist magazine, Solvang has 250,000 visitors a year who eat Danish smorgasbord and buy Danish silver, porcelains, glassware and painted trinkets.

What we couldn't figure out is what happens to all those people at night. By 10 o'clock (if we'd known we would have gotten there earlier) there is no one in the shops or on the streets. Only an occasional barking dog in the distance. Rather like a closed movie set -- eerie and uninhabited. But, if you walk behind the Danish exteriors, up the back streets where the shopkeepers must live, the Danish mystique falls away. In its place are the little wooden houses looking like any others in California's small towns.

(With so much ocean view ahead -- or behind, depending on your direction -- some coastal travelers heading for Solvang will turn off 101 at Santa Barbara, or a few miles north of Buellton, and follow Rte. 154 through the San Marcos Pass. The mountain scenery and the views over Lake Cachuma are spectacular).

We had wanted to stay in San Luis Obispo that night, a town about 60 miles north of Buellton. There was "no room at the Inn," . . . the Madonna Inn. But I'm getting a little ahead of the story because I haven't mentioned the scenery yet, and around Santa Barbara it is lovely.

The Pacific Ocean, unlike the Atlantic, is blue, always a surprise and treat for Easterners. Only occasionally do the offshore oil drilling platforms mar the view. Several miles north of Santa Barbara the coastal highway goes inland and the little of it you see before the road takes a sharp right turn at Gaviota give you no inkling of what lies ahead. If you never drive further north than San Simeon you'd think you were the victim of another kind of hyperbole.

We had hoped to stay at the Madonna Inn because a Los Angeles friend had smiled when she said it's "The place."

The Madonna Inn belongs to Mr. and Mrs. Madonna, who, as our resident philosopher noted, were really lucky. "Most people can only build a little grotto in their backyard in Queens. This is really the American dream. It's fascinating to see someone carry out a fantasy."

Everything at the Inn that is paintable is painted pink: pink lamposts, pink plastic rocks, pink gas pumps at the gas station, which also boasts a copper-covered counter, a pink ceiling, and etched glass windows with a wrought iron light figure.

What isn't painted, Alex and Phyllis Maddona have carved, cut out, etched, tiled or covered with stained glass. In the dining room a gilded girl swings above the diners on a motor-driven gilded swing.

"San Simeon is what the Madonnas would have done," said out latter-day H. L. Mencken, "if they had the money. They substituted imagination." Or, as the original Mencken observed: "No one ever went broke underestimating the taste of the American people."

As we drove away from the Madona Inn, four busloads of senior citizens pulled up for lunch and a look. "Isn't it gorgeous," said the lady in the hot pink polyester pants suit with hair to match.

The mission at San Luis Obispo is light years removed in feeling, and time, from Solvang or the Madonna Inn.

El Camino Real, The Royal Road, as it was called when the Spanish were colonizing in the late 1700s, is dotted with 21 missions, in various stages of repair. "Authentic replication" is lacking, fortunately. The missions tell you as much about life along the coast 200 years ago as the modern-day monuments tell you about the 20th century.

It's difficult to recommend how much time to spend at the Hearst Castle: a month isn't enough; a half day may be too much. To get anything more than a sense of the vastness of the buildings and of William Randolph Hearst's wealth, you would have to visit each of the rooms on the tour a dozen times.

Did Hearst really enjoy his collections? Did he even know what was in them? There is the sense of acquiring for the sake of acquisition. And there are two other lasting impressions: the zebras grazing on the lawn with the cows (Hearst collected wild animals, too) and the Del Monte catsup bottle and French's mustard jar which were always put on the refectory table in the 15th century gothic monastery dinning room. The walls, ceilings and fireplace in the 67-by-27-foot room with 27-foot-high ceilings had been moved (as were rooms from other European castles) in their entirety to Hearst's castle.

Along with the mustard jar, catsup bottle and paper napkins, embossed with Hearst's initials, were massive pieces of antique Spanish and French silver. Hearst, we are told, used those 20th-century touches "in keeping with the tradition of dining, at what he called the Ranch" and "to make his guests feel comfortable." Only William Randolph Hearst could get away with it.

The Castle, which made a profit of $500,000 last year, belong to the state of California. Because of Proposition 13, the Castle cannot keep those profits which are sorely needed to expand the tours, already running at capacity. The money must be returned to the state's general fund where it is used to subsidize less-profitable operations.

Around San Simeon the land is fairly flat. The sea sparkles and seems friendly; cows graze beside it. The hills to the east are gentle and don't begin their rise until they are some distance from the road and the sea.

It isn't until you drive north of San Simeon that you begin to see the stuff of which California picture postcards are made. The road narrows because it has been cut out of the mountainside, part of the Santa Lucia Range against which the Pacific Ocean beats and swirls.

As the traffic thins out, the fog rolls in. That's something else no one tells you about. The most spectacular of the coastal scenery is often shrouded in fog -- winter and summer. It comes and goes, allowing occasional glimpses of distant rock formations and glistening blue sea.

It is in this part of the coast that you should begin your search for the sea otter, a cuddly relative of the land otter, which environmentalists are struggling to save. Friends of the Sea Otter, out raising money on the streets of Carmel of a Saturday afternoon, are locked in a classic struggle with the abalone fishermen.

Otters eat many times their weight in shellfish, and abalone fisherman hate them. These otherwise lovable little animals are said to lie on their backs all day among the kelp beds, so anytime we saw kelp we stopped and searched . . . and searched . . . and searched.

Wherever we looked the natives promised that they had been there "just that morning." We never found them, but I understand the San Diego Zoo has some.

If you have time, you ought to spend a day in Big Sur, preferably at Ventana. A small, rustic resort perched atop a steep winding driveway with swimming pool, saunas and community hot tubs (his, her and theirs) and a restaurant, it is managed by young "mellow" men and women who are friendly, helpful and so laid back they can't distinguish one guest from another even though there are only 24 rooms.

Ventana's restaurant, which along with the resort has the requisite views of the Pacific, has good food, probably the best around the area. Nepenthe, a well-known restaurant just across the highway, whose service would have been described as hippie 10 years ago, is even more laid back than Ventana. It's better to drink there than to eat . . . or inhale the smoke.

Then there's Carmel, at the southern tip of the Monterey peninsula, where the people who wondered what America was coming to in the late '60s have retired. Carmel -- "one big shopping center on the ocean." White Flint Mall, only bigger and open air.

"Carmel is Solvang for keepers," commented our peripatetic philosopher. "Solvang is an out-and-out fraud. It's fun. Like Coney Island. Carmel really died and went t heaven and lived happily ever after."

The downtown business district is clogged with California blondes (with an E) in their tight jeans and halter tops, and blonds (without an E) in their tight jeans and gold chains along with the ladies in their Lily Pulitzers and Pappagallo shoes.

It's a short ride to 17-Mile Drive around Pebble Beach, famous for its golf courses and its estates. Famous, too, for charging tourists who want to gawk and view the ocean (and look for sea otters) $4 a carload for the opportunity.

It's beautiful. It really is. But is it possible to get sceneried out? If I were recommending a trip up the coast, I would tell people to forget about Pebble Beach if they'd driven through the Santa Lucia Range. Besides, there's more to come: the cliffs, the whirlpools, the sea gulls, the sand dunes . . . and the beaches as you get closer to San Francisco. San Franciscans are lucky, but then they don't have to leave town to see the kind of sunset which rivals anything along the coast.

The Big Sur ambience, where ties are out of order and hot tubs are communal, is replaced by the elegant Stanford Court in San Francisco. Small handsomely decorated, attentive, the hotel has all the comforts plus a location on Nob Hill where both cable car lines converge.

After a few practice trips you, too, can learn how to hop on and off them while they are moving, hang precipitously over the side as they make sharp turns and eventually convince the brakeman you are a native.

But if you get lonesome for Solvang or the Madonna Inn, you can always take the Mason Powell Street car to the end of the line and visit the Wax Museum on Fisherman's Wharf, where there is an "authentic replication" of the King Tut exhibit . . . all in plastic.