http://sf.funcheap.com/
This is the greatest site and guide of what you can do in SF. Hitting the touristy places are actually fun. The locals are a bit jaded, c'mon when is the last time you did the cable car tour? Check out Coit tower, check out the bars and weird shops in the Castro, there are super good hole in the wall restaurants in the mission district. Go to the academy of sciences and check out the oldest and most depressing albino alligator ever lol. Go to Ocean beach on Friday night and watch 60 squids drag race parallel to the beach. Barf ride for you locals... Or take obscene photos in the exploratorium and laugh maniacally when the school groups go into the "shadow capture room." There really isn't enough time to do much though so choose wisely.