The tour of Alcatraz was great. The information as well as the sites you get to see are amazing. I recommend the audio tour (I think they all come with audio). It is great to be able to follow all the different things that happened there as well as hearing about the attempted escapes and what not. Be sure to bring a camera as there are plenty of picture taking opportunities. Be prepared to be amazed at how well they lived despite the fact that it is a prison.
One little fun fact they tell you is that they fed them very well with great food and all they could eat to make it less possible for them to take the mile swim to land.