What are some touristy things to do in San Francisco?

Hi All:

I will visit SF in October, and I am planning my itinerary now. I won’t have a car so I will be on public transportation. I will check out Pier 39 and Alcatraz, but I need some of your suggestions. Is there a rail system that goes across the Golden Gate Bridge? I am staying at the Westin St. Francis in Union Square. I would appreciate any tips. Thanks in advance.