Any time I have friends or family who come to visit, I always recommend a trip to Alcatraz. It's quite honestly one of my favorite places in the Bay Area...is that weird? I think it's absurdly beautiful, and the history is just fascinating to me. I love that it's a whole big experience, from taking the ferry, to stepping off the ferry and exploring, to the audio tour that takes you through the prison and includes interviews. I've been three or four times now but I still go any chance I can.