Restaurants in the Washington area, having already learned (with varying degrees of consistency) how to please palates in subtle and various ways, are beginning to serve up sumptuous and striking feasts for the eyes.

The piece de resistance might very well be Clyde's at Tyson's Corner, whose 9,360 square feet are as much museum as restaurant. There are waterfowl paintings by Robin Hill, art glass by Kenneth von Roenn, chairs by Peter Danko. Everywhere there is something that has been sculptured, carved, crafted, painted or wrought. No detail seems to have been overlooked. cFor example, the pushers on the revolving door of the main entrance were done by sculptor Albert Paley.

The look is Art Deco. Or Art Nouveau. Or tongue in cheek. Or something of each, and then some.

Manager Mark Walsh says of the customers, unapologetically, "They are overwhelmed."

But enough of them apparently have recovered to come back for more. In its first year of operation (opening day was June 24, 1980), Clyde's at Tysons has grossed $6.25 million -- almost 40 percent more than owners Stuart Davidson and John Laytham had projected.

The $5.7 million "roadhouse," as its owners quaintly refer to it, has attracted widespread attention in the restaurant industry. There is a steady stream of visiting proprietors from other establishments, and in recent months there have been detailed articles in Interior Design, Restaurant Design and Nation's Restaurant News pondering the implications for the industry.

As for where Clyde's fits in with other restaurants, Regina S. Baraban, editor of Restaurant Design, says: "Clyde's is deserving to be called its own statement. It is not a knockoff."

While Clyde's has been the focus of most of the attention, there are other area restaurants that are making an imprint with their design and architecture. a

On K Street's restaurant row in downtown Washington, most of the dining rooms, even those with first-rate cusine, play it safe with black or red accented by gold or brass trim. Some of them try to proclaim a nonexistent elegance with little teardrop chandeliers. But Piccolo Mondo, near 19th Street, is a stunningly elegant exception to the rule.

Piccolo's entrance, like the rest of the decor, is Art Deco: a silver grillwork ceiling, mirrored walls with graceful arcs etched into their surface and stainless-steel railings suggesting bundles of papyrus (Deco took some of its inspirations from Egypt in the early 1920s, when King Tut's tomb was discovered by English archeologist Howard Carter). Accenting the turn of the staircase is a bouquet of rubellum lilies in a crystal vase.

"The entrance had to be dramatic," said co-owner Michele Santillo. "If you're going to entice someone to come downstairs you better do something dramatic. You can't bring a plate of food outside for them to smell."

The centerpiece of Piccolo is its bar. The frosted glass top is illuminated from underneath and the edge is rounded off with a swell or horizontal stainless-steel fluting suggesting, again, bundles of papyrus. Behind the liquor bottles is a boldly decorative design, in the basic colors of plum and gray, suggesting a lily.

For Santillo, Piccolo Mondo is an aesthetic achievement, but with some practical results in a business that is crowded with competitors. "We have fought our way onto K Street with decor," Santillo says.

But achievements of design do not always guarantee success. The short, spectacular life of Le Premier is a prime example. The restaurant, with its stage-set look, attracted immediate attention when it opened last fall. Progressive Architecture called it one of "the best-designed restaurants in Washington."

The look was Art Moderne: illuminated columns of frosted lucite, a pinkish ceiling that broke into a curvy cloud and stagey lighting. Gossip columnists quickly noted that the prominent tables on the front platform were favored by such item-rating figures as Zbigniew Brzezinski and Hodding Carter. Le Premier looked as if it was going to be a hit with a long run.

But Le Premier's stage was darkened earlier this month after not enough diners came back for return engagements.

"The problem was not the design," said Kensington architect Donald Little, who created Le Premier with his partner, Dennis Cross. But Little, noting that Washington restaurants tend toward the heavy, dark look, acknowledged: "We obviously were bucking tradition. It remains to be seen if what we created will be picked up by other restauranteurs. It's happened in New York. It's happened in San Francisco and Los Angeles and Chicago. But Washington is a very traditional town."

A warning was sounded by John S. Cockerill, executive vice president of the Restaurant Association of Metropolitan Washington: "The public can be enthralled by a restaurant's design, but they won't go back unless the food is good and the service is good. Sometimes too much attention is devoted to design."

Yet showy design continues to burst onto the area restaurant scene. Pronto has brought the American look -- clean, casual, airy elegance -- to Harborplace at Baltimore's redeveloped Inner Harbor. In one dining room, the basic elements are white tile, brass railings and overhanging white enamel industrial lamps. The exposed pipes and ducts in the ceiling are white, too.

Just the opposite effect is created by Henry Africa restaurant in Alexandria, which emphasizes the ornate (a mahogany bar with an illuminated onyx top) without becoming heavy.

What is happening here and there in the Washington area is part of a nationwide trend, restaurant design experts say. "The trend, is toward upgrading design, using architects and designers," says Restaurant Design magazine's Baraban. "The answer is competition. Ambience and environment sell as much as food . . . .Clyde's and other spectacular statements indicate that people do respond to good design. And the more that restaurant owners know this, the more they will put in design and architecture. rThere is a bottom-line payoff."

Good design can be expensive -- Clyde's flourishes cost an extra $1.5 million, according to manager Walsh -- but it need not be. Berkeley, Calif., designer Stephen A. Shubel did the widely praised interior of the 101-seat Roundtree in that city for $20,000 (not counting the kitchen). He used black and white tile on the floor, $2-a-yard canvas that he painted himself and Breuer chairs.

Indicating another trend, Shuybel said of Roundtree, "It's more open, the tables are closer together. When people go to a restaurant today, they want to meet other people and hang out."

The trend toward better design, created by architects and other professionals, is not limited to toney restaurants. Warren Platner, the New Haven, Conn., architect who helped create the acclaimed Windows on the World in New York's World Trade Center, is busy doing the restaurant adjacent to an Apex-discount shopping house in Warwick, R.I.

"Some people might call it a greasy spoon," Platner said, "but greasy spoons sometimes have good food."

Platner is putting a large gold tulip on top of his pyramid-shaped restaurant. "It'll be visible from the freeway," he said. "It's aggressive, but not garish."

The new emphasis on design seems to be catholic enough to include Platner's giant gold tulip and Pronto's sleek white look, but Chicago designer James E. Miller (East Bank Club, Hillary's and Sweetwater) said "people are fed up with clutter. There is a return to casual elegance, more of an underplay of accessories. The colors are soft and attractive. There is a feeling of quality."

The last word on what restaurant design should be (and not be) probably should be reserved for Joseph Baum, the New York consultant who "produced" (his word) the Four Seasons, Forum of the Twelve Caesars, Charley O's, Tower Suite and Windows on the World, all in New York, and was in charge of the "conceptual program" for the redone restaurant at Washington's National Gallery of Art and the cafe in the East Building.

"Restaurant design has too often been the shallow use of gimmicks and merchandising artifice," he said. "Good restaurant design means one expresses style by distilling the essence of the time. We immerse ourselves in the present. We don't believe history lurches forward on the unrelated Tiffany novelties of the past."

"I'm not enthralled with the shock value of the incongruous -- the salad in the bathtub, the stage-set restaurant. That leaves no elbow room for the mind. I'm more interested in a restaurant that is evocative, that conjures taste memories. . . that are both spiritual and real."