Washington has dozens of Mexican restaurants for all tastes and types; every one of them is somebody's favorite. Here's just a smattering, reviewed by Phyllis C. Richman and her staff.

CHI-CHI'S OF ROCKVILLE -- 95 Rockville Pike (in Wintergreen Plaza), Rockville. 251-0544. Open daily. AE, CB, DC, MC, V. Reservations accepted only for parties of nine or more. Full bar.

The key to eating at Chi Chi's is to go with limited expectations. Be prepared for Mexican food that's flavored with extraordinary timidity, and understand that the variety extends no further than the usual taco-enchilada-burro family of foods. Then you'll be prepared to appreciate the plusses of Chi Chi's: some reasonably good (if dull) Mexican dishes, big portions, a series of handsome dining rooms and low prices. The most impressive entrees are the chimichangas, fried wheat-flour tortillas rolled around meat fillings and topped with sauce and sour cream. Also admirable is the chile relleno, its egg batter airy, its cheese light and its green chile peppers retaining some life. The beef enchiladas have nicely chewy tortilla wrappers and plenty of coarsely ground beef inside. But the burro wrappers are tough, over-thick and under-cooked, and the tacos are so bland they'd do for an ulcer diet. To wash things down, avoid the sangria and rely on the good Mexican beer. For dessert, stick to plain ice cream.