We didn't do the excursion through Disney, but we did visit the fort while we were in Nassau last year on another cruise. We walked to the fort, and went up the Queens staircase, which is right next to the fort. It is only a 10 minute walk, and it's through a pretty safe part of town. The fort is free, as well as the staircase, although locals will be around wanting to tell you about it for a small donation. When we went, the watertower was "closed for renovation". It looks as though it has been closed for a few years... I guess you used to be able to go up the elevator of the tower for a quarter and see the town. The view is pretty good from the fort though, you can see most of the town, Atlantis, and all the cruise ships docked in port.