Open daily for breakfast 7 a.m. to 10 a.m., lunch 11:30 a.m. to 2 p.m., dinner 6 p.m. to 10 p.m., tea 3 p.m. to 5:30 p.m. Sunday brunch 11:30 a.m. to 2:30 p.m. (Marley's lounge: Buffet lunch 11 a.m. to 2 p.m. Monday through Friday, open daily 11 a.m. to 1 a.m.) AE, CB, DC, MC, V. Reservations suggested. Valet Parking. Prices: At brunch, entrees $6.50 to $12; at lunch, entrees $5.50 to $12.50; tea $7.50. At dinner appetizers average $6, main dishes $13.50 to $22.50 and more; desserts $2.50 to $4.75. Full dinner with wine, tax and tip about $40 a person or more.

Washington's biggest eating place, one would guess, is the new Convention Center. One of the smallest is just up the street in the Henley Park Hotel, where the sun smiles down through a skylight on the pretty little dining room of the Coeur de Lion. It took the heart of a lion to open a top-price luxury restaurant at 9th and Mass., where one is more likely to expect a burger shop than white glove service. So the Coeur de Lion, for all its flaws, is an oasis.

For those who value beauty and service above all, Coeur de Lion will be a real find. For those who see cuisine as the focal point, it does not yet meet the competition, particularly for the price. The Henley Park has priced its menus on a level with the best--soups starting at $3.75, appetizers from $5.50, main dishes frequently above $16 at dinner--but the food is erratic, quite good or clumsy, depending on your luck and timing.

The Henley greets you with valet parking and a warm welcome, then offers the choice of a cozy bar furnished in dark woods and tapestries, the brick-lined skylit atrium or another dining room every bit as beautiful, lined with murals and stained glass. At teatime you can sit at an antique desk with a silk-shaded lamp and look out windows of old mottled-looking glass. And at lunch you might find a buffet--the lone bargain at a mere $6 for three courses--in the bar, with piano music for entertainment. The dining rooms are set with handsome German china and luxurious glassware, the candles are tall white tapers and the flowers might be tea roses or baby roses, certainly something romantic. The Henley's rooms are ornate and sumptuous, with no detail ignored. A European-looking inn in downtown Washington is such a pleasant surprise that it warrants scheduling an afternoon tea or Sunday brunch.

Tea costs $7.50, and while the service can be slow and no single component could be considered wonderful, it adds up to a special treat. Your cup is warmed with hot water, and you are asked how strong you like your tea. The sandwiches have been bland and a little stale, but are painstakingly trimmed of crusts. For the scone there is a tiny pot of rich but runny Devonshire cream, and fresh fruit serve as garnish. A bit of pastry, a tiny jar or two of jam, a couple of rather good chocolate truffles add up to enough for a filling late lunch and a most delightful excuse to linger away the afternoon.

The kitchen is trying, but sometimes too hard. A cold lobster is overdecorated with a kiwi and egg white eye, but who could fault a kitchen that cuts the meat for your convenience and lays it back in the shell over a bed of crab salad. It emerges a highly decorated plate of pretty good food.

Most of the food is pretty good, but rarely is it a knockout. Liver with avocado at one day's lunch was perfectly cooked, but the liver was darker and stronger than a luxury restaurant should serve. Salmon might be poached to soft smoothness, but the fish itself has been a touch bitter and its pale green sorrel sauce no more forthright than a cream sauce. A sandwich of crab, chicken and bacon sounded intriguing, but impossibly awkward to eat and, from the unripe tomato to the dry and crumbly chicken to the cold bacon, a sad mess. Its few lumps of snowy fresh crab disguised stringy crab underneath, which could have been canned or frozen for all its taste.

Dinner has been distinctly better. The appetizers include dishes so ambitious as pheasant and duck pate en croute with pistachios, truffles and two kinds of wild mushrooms, in a caraway seed sauce; or something so simple as fresh caviar with an assortment of vodkas. There is an attempt at originality with each dish: snails are in a pastry shell with garlic bordelaise; crepes are filled with curried shellfish, poultry and fruit; soups range from cream of avocado to a duck consomme with quenelles of duck. Main dishes are the familiar luxurious meats--beef filets, duck breast, lamb, veal scallops--and fish--salmon, swordfish, trout, sole, lobster. But the trout and lobsters are stuffed, the sole layered with fish and lobster butter forcemeat, the lamb moistened with a mint-flavored bercy sauce, the duck breast flavored with green peppercorns or red wine. What I have tried has been nicely prepared, the sole with lobster mousse moist and fresh-tasting, its sauce delicate and its topping of julienned vegetables a crisp contrast. A creamy melange of lobster with mushrooms and truffle could have been faulted for tasteless canned truffles out of season or for lobster meat a touch dry, but in all it was a very nice dish. And if breast of duck and roast lamb were clumsily sliced and not particularly attractive just spread out on their plates, they were both cooked just right and trimmed impeccably and sauced with quite pleasant brown sauces. Along with them came asparagus in a fine hollandaise and good browned potatoes. And following them one can have an utterly delicious English trifle with fresh berries, its beautifully soft and eggy custard with just enough alcohol to perk it up but not enough to drown the delicate taste. Skip the mocha mousse and the pastries.

All in all, though, the Coeur de Lion is overpriced. Good but not outstanding, its food is not competitive with the other French restaurants in its price range.

With the Convention Center nearby, the Henley Park's neighborhood is presumably on the upswing. By the time nightlife is restored to the area, the Coeur de Lion may be ready for it.