Walking in/around a big cement building on an island. Being outside is kinda nice... fresh air and views and stuff.

The audio tour is good, do that. Also watch "So I married an Axe Murderer" with your friend before you go if possible. It has a really funny part in alcatraz with Phil Hartman playing a tour guide named Vicky. The movie is full of other fun SF stuff too.

I've tried to do this with visiting friends in the past and tickets are usually sold out a couple of days in advance.

KRISSY'S GOING TO JAIL!!

it was fun and the views are super good, but the tourists will totally annoy you to death.