What is it really like in San Francisco?

I always wanted to go to Santa Cruz, and most likely will be flying into San Francisco. My friend really wants to check our San Fran( the trollies, landmarks, etc.) Is every bar in San Francisco like the Blue Oyster from the Movie Police Academy. Not trying to be sarcastic, but just want to know if the the gay population is that noticeable. I am not against gays, just wondering.