Wasn't my thing really, go for an hour or two but I wouldn't spend much time there... super touristy and also expensive.
If you're into food there are a bazillion awesome restaurants so you'll love it there... the Ferry Market building kicks ass. Make sure you take some time and head up to Napa/Sonoma as well, hit some wineries for tours etc.
I'd also recommend you check out the Mission district for the best mexican food, Union Square for super expensive shopping, Pacific Heights, Marina District, Chinatown (even though it is small), Golden Gate Bridge, etc etc. Lots to see and do... can't wait to go back.
Check out cellspace.org or false-profit.org and see if there are any shows happening.
Stay at the pheonix motor inn.
get real high and then watch 6 cops with weapons drawn take down a thug across the rd from your hotel as you pull up in a cab.
Then after partying all night find a random cab driver who drives faster than anyone you've ever met in your entire life (literally jumping the car over bumps) to take you home, tip her an extra $10 because the ride was better than any rollercoaster you've ever been on.
avoid all the tourist attractions and explore as a local would. your time is limited, so don't spend it verifying photos you've seen. there are books and websites for that.
for example...if you do the tourist thing, like fisherman's wharf:
you could miss out on something like the haight street fair:
food and wine are the best things you can take advantage of. the year-round availability of local organic produce, meats, seafood and wine raises the bar when compared to other cities. you don't have to spend a lot to have an amazing meal here unless you want to.
now that summer is here (weather is hit/miss now - late sept/early oct is best) there are lots of outdoor events. street festivals/fairs are going on (every wknd til oct). last sunday was haight/ashbury st. fair; tomorrow the north beach festival. stern grove festival is a series of free concerts every sunday in the park that starts tomorrow with aimee mann... ozomatli is in late august.
let me know the dates and i'll let you know what's going on.