Alcatraz is supposed to be pretty cool (haven't been myself), but if you want to go make sure you buy tickets well ahead of time.
Take the trolly at Powell station
Alcatraz- never been, but you normally have to get online reservations months
in advance. So don't delay if you want to go there. There are other ferries (to Angel Island, Tiburon, etc, which do not require reservations.
"Trolley": I think yojimbo means the cable car
. Nice touristy ride to the Fisherman's Wharf area. BUT, if you don't want to wait in a very
long line to get on, you have to get there before 9:00 am - (and most gay tourists are not out of bed at that hour.)
You can find a lot of helpful information (and even pose questions which will be answered), on the "San Francisco Travel Forum on tripadvisor.com .
SF is a big city (although with provincial attitudes) packed into a small place. There is a lot here - So you should tell us what interests you - For all we know, you might want to spend all your time in gay venues - or, OTOH in art museums - or trendy resturants. And some things are seasonal - so if you said when you were coming, we here could be more helpful.
One thing that is seasonal is the rain - if coming after mid-October, bring an umbrella - you may need it.
Lived here for many years. Feel free to PM me if you want more specific recommendations.