1800 Market Street
Pride is celebrated in SF every June and is really quite disverse. Obviously you have the GLBT community but many straight people also come out to support it and to just be with their friends. Pride in SF is definitely a crazy, one of a kind experience. Dykes on Bikes. The San Francisco Bears, Gavin Newsom... you get the idea. I have to make it clear that I understand not everyone is comfortable with this, but I thought it was worth a mention nonetheless and if you are, I recommend it if you're in town. Granted, leave prudeish-ness at home because as I said, this is definitely an experience!
For more information see http://www.sfpride.org/