Quoting kryptonite
You MUST go to the wharf, I know its quite touristy, but all the same it is a great place to go - I don't live in SF but I'm there most weekends and still find myself wanting to go to Pier 39. Check out the sea lions at the end of the pier, I love just sitting there and watching them...the mimes are great too, and keep an eye out for "the bush man", he's hilarious.
And check out the Pier 39 stage at the end toward Alcatraz, down near the wild loud sea lions. If a magician intro's himself as Fred, that is my nextdoor neighbor!!!
Did I mention museums? Asian Art has become one of my faves and now the de Young is nearly reopened after retrofitting, plus Museum of Modern Art, Palace of Fine Arts, Palace of Legion of Honor [check out huge Rodins] and the Maritime Museum.