This is one of my all-time favorite places to get festive, but it's not for everybody. Cha Cha Cha is not a meal; it's an experience. Put your name on the mile-long list, crowd into the minuscule bar, and sip sangria while you wait (try not to spill when you get bumped by all the young, attractive patrons who are also waiting). When you do finally get seated (it usually takes at least an hour), you'll dine in a loud--and I mean loud--dining room with Santeria altars, banana trees, and plastic tropical tablecloths. The best thing to do is order from the tapas menu and share the dishes family-style. Fried calamari, fried new potatoes, Cajun shrimp, and mussels in saffron broth are all bursting with flavor and accompanied by rich, luscious sauces--but whatever you choose, you can't go wrong. This is the kind of place where you take friends in a partying mood, let your hair down, and make an evening of it. If you want all the flavor without the festivities, come during lunch. There's a second, larger location in The Mission District, at 2327 Mission St., between 19th and 20th streets (tel. 415/648-0504).