r/Sanfrancisco, I'm visiting next weekend, what should I see?

I'll be visiting San Fran for two days, I've never been to the West Coast and I'll be meeting some friends, but I have a huge chunk of saturday to myself, what is there to see?

Specifics: Places with good beer and a wide selection (maybe some German brands?!) Big architecture/photography nerd, so big landmarks and such (All I can think of is the Golden Gate and Alchatraz) and big parks!! Also, does San Fran have a bike share program or bike rental system? It would be nice to rent a bike for a day or so to cruise around on.

Thanks!