With only a day and a half, I would suggest to pass on Alcatraz for this visit. You'll have plenty of stuff to do already. :-)

I went to Alcatraz on a beautiful day and enjoyed the boat ride and city/Golden Gate bridge views as much as Alcatraz itself.

I didn't do the audio tour...just to be different and everyone else had them. It was so quiet inside as everyone else was listening through headsets. I was also able to give my daughter (8yr) info that she could handle..

I also loved Alcatraz,it was one of the highlights of our trip to SF, pay the $ and have the Audio - money well spent. J.