BFrank lives in The City and would know more where to stay...he is a font of knowledge in that regard.
When I go, I try to book a room in the SF Airport area then CalTrain it into SF. Saves the aggravation of finding parking besides there are several 4-star hotels there and on Priceline, you can usually save a bundle, too. The worst you can do in that range is stay at a Hyatt, Sheraton, Hilton or DoubleTree.