Open for lunch Monday through Saturday 10:45 to 3 p.m., for dinner daily 6 p.m. to 11 p.m., Sunday brunch 10:30 a.m. to 3 p.m. AE, D, CB, V, MC. Reservations. Prices: brunch $18.75, lunch $7.50 to $14, dinner $11.50 to $16.

Sunday brunch, that all-American meal, is said to be taking Paris by storm. Maybe that's why the French, belatedly entering the Washington brunch competition, are doing it so well. Two of the most satisfying

buffet brunches in town are at hotels that have recently come under French influence.

Nobody prepares a better Sunday brunch buffet than the Rive Gauche at the Georgetown Inn. And nobody combines a buffet--of considerable variability in quality but with enough good food to make it worthwhile--with such a sumptuous setting as the Hay-Adams' Le Danielle.

Le Danielle is a room with a view--a view of itself, a glorious dining room. The ceiling is carved and painted wood, dripping with monumental chandeliers. The wood- paneled walls are delicately carved, and between the two dining areas are metal grills inset with stained glass. Windows are composed of diamond panes. The fireplaces are stone. The chairs are deeply cushioned with leather. And on the tables are brass lamps with pleated silk shades. Steeped in tradition, the dining room looks as if it could be a Senate chamber or a special guests' reading room of the Library of Congress. Its ornateness and striped tent-like ceiling border give it a Moorish cast. The Villeroy and Boch china and the orchids in crystal globes bring the luxury right to the table.

All of this is a special treat on a Sunday afternoon devoted to a leisurely champagne brunch.

The food itself swings widely between grandeur and embarrassment. Salads of shrimp with cucumbers and mint, a pungent and delicious p.at,e, a toss-it-yourself salade nicoise with fresh, firm green beans and several brightly colored and brightly flavored vegetable salads start brunch with a flourish. Some are gritty from a heavy hand with dried herbs, but they are nevertheless invigorating.

The brunch breads need improvement, especially the doughy and tasteless danish pastries. As for the steam-table dishes, most of them belong at a government cafeteria rather than in this splendor. Shriveled quiches, chicken turning soggy in an odd red mushroom sauce, seafood steaming away in a cream sauce. The vegetables stand the heat no better--white rice with some wild rice mixed in remains good, but the cauliflower, snow peas, spinach and such had wilted and dried out, though one could tell they had started out fine. A kulebiaka with a buttery puff pastry and an agreeable fish stuffing we caught before the heat massacred it. And eggs benedict were rescued by the kitchen's cleverness: the poached eggs remained just soft enough in a warm water bath; the Canadian bacon and toasted English muffins were kept dry and warm in another pan; and the hollandaise was kept smooth and tepid in a third container. Assembling them to order rendered these eggs benedict an excellent brunch dish.

Le Danielle served no smoked salmon or oysters on the half- shell; this was a meat-oriented brunch, culminating in a good, rare roast beef, a high-quality ham on the bone, well-seasoned and rare lamb roast and a stuffed veal that unfortunately tasted bleached of all flavor. All were carved to order. If your idea of Sunday brunch is actually Sunday dinner, this one will suit you.

The champagne, quite drinkable, is poured frequently. And if you splurge on orange juice, you will find it worthwhile, for it is freshly squeezed. The coffee could be stronger; but the espresso has solved that problem. The desserts are all show: sugary, heavy, grainy pastries of flossy beauty.

Of course, one can lunch or dine at Le Danielle the rest of the week, too. And it is not a bad idea. But at the price, it is not likely to be at the top of one's list. The standing menu is standard French-restaurant fare: Dover sole, duck a l'orange (for two), Bibb lettuce salad (at $4.50). You will find strawberries and asparagus out of season. And the daily specials reach beyond the routine: oeufs en gel,ee, duck with sauerkraut, double lamb chop in puff pastry.

Their execution is professional if not exciting. The eggs in aspic, for instance, look beautiful inset with petals of leek and carrot. And the egg inside had been perfectly poached. But the glimmering aspic was salty and rubbery, tasting several manufacturing processes away from a stockpot. Other appetizers--creamed seafoods in a scallop shell, leek and potato soup--were pleasant but without distinction.

Main dishes were similarly routine: Veal White House with morels and a very salty cream sauce; tournedos thick and skillfully cooked, in a correct brown sauce; duck that was crisp and fat-free, though stringy and dank-tasting from its reheating. The lamb chop in puff pastry was the best of the main courses we tried; the kitchen obviously starts with good lamb, then trims and seasons it well. And like the kulebiaka at brunch, its puff pastry was buttery and flaky. But inevitably, with such a dish, the pastry is soggy inside. The chop came with an extravagant bouquet of fresh vegetables--mushrooms, broccoli, green beans and the like. All this on charming oval flowered plates, served from silent rolling carts by waiters polished in their trade.

The desserts are the same as at brunch: lots of show and not much substance.

One of the assets of Le Danielle is its wine carte, a long list of French vineyards, though no in-depth array of vintages. What is special about it is the two-page list of half-bottles, whereas few other restaurants offer more than one or two choices.

And then there is the dinner music, issuing from a mirrored piano. A lovely bonus for the environment, but not when canned music is substituted during the pianist's break.

There seem some insurmountable obstacles in turning the dining room of a grand hotel into a compelling restaurant in its own right. And Le Danielle is clearly trying to overcome those obstacles. So far, it has left me unconvinced that it can be done. But as long as the management keeps trying, I'll keep hoping.