Here's a quick list
Golden Gate Park - huge park with museums, japanese tea garden and an aquarium. also located near the hate-ashbury
Presideo - old military base now a park near the base of GG bridge
Exploritorium - hands on science museum - a must see if you're at all geeky.
Angel Island park - The west coasts Ellis Island where chiniese and japanese imigrents came through. Rent a bike and take the ferry but it's an all day thing.
China town and Japan town.
http://www.bondage-a-go-go.com/ - long running fetish party