I haven't been up to San Francisco for a couple of years, but here's a list of my must-sees.
Alcatraz--Now I haven't been there (believe me I tried ) very popular, so go early or book in advance.
Cable car ride -- There are three lines. Both the Powell-Mason and the Powell-Hyde lines begin at Powell and Market streets. Both have good views, however the Powell-Hyde line does take you right pass Lombard St.- the crookedest street in the world.
China Town
Golden Gate Bridge
Fisherman's Wharf (Boudin's for clam chowder in a sourdough bread bowl, take it outside and enjoy.)

Have fun, and we're looking forward to that trip report.