There is really nothing at the port so venturing afield is a virtual necessity. I chose a tour to Kennedy Space Center, although I have been there several times in the past. I think it's a must do for anyone who hasn't been and I loved my visit there. One thing to look forward to in the future will be the unveiling of the Space Shuttle Atlantis in Summer 2013. Other options are shopping or theme parks in Orlando, and shuttle to Cocoa Beach for either beach or shopping.
Nassau is a nice but crowded town. I went to Ardastra Gardens which is really more of a zoo. The animals seemed to be mostly African, as well as a large collection of birds. There are 2 interesting shows, parrot feeding (audience participation) and marching drill by pink flamgoes.
Apparently good for beach, snorkel, and shopping, there was little to offer in cultural and historic attractions. I took the ship's "Island tour", and it was mostly looking at upscale houses and a lengthy shopping stop.