The Tonga Room is one of the last remnants of that giddy era when umbrellas sprouted from every coconut, Trader Vic ruled the cosmos, and ukuleles could be heard from North Beach to the Richmond. The crucial element that separates the Tonga from its Polynesian competitors past and present is, of course, the tropical downpour. Sure, the totem poles and the jungle foliage and the ship's riggings and the fertility-god icons are lots of fun, but your voyage to the tropics really begins when the thunder starts to rumble, lightning flashes across the ceiling, and a torrential rain pours down into what used to be the hotel swimming pool. The illusion of suddenly finding yourself in some thatched-roof tiki paradise is helped along by the terrific house cocktails. Not only are they delicious concoctions in the rum-coconut-fruit juice tradition, they're served in hollowed-out pineapples, yardstick-tall flagons, and ceramic vessels of every variety, each of them festooned with speared fruits, blossoming flora, and those indispensable tiny umbrellas. Every weeknight from 5-7 p.m. there's an all-you-can-eat happy hour buffet of spareribs, pot stickers, crudités, and other quasi-delicacies for $6 plus a one-drink minimum. Dance music, meanwhile, is provided by a combo floating on a raft out there in the middle of the storm.