I am taking a cruise to Nassau as well (but on Carnival Fantasy) and have been told that Atlantis is an incredible resort to see which has a great underground "dig" (aquarium) that you can take a taxi to on your own to and pay $25-$35 dollars per person or you can do it as an excursion. Others have also mentioned Queens staircase, the straw market, and Dolphin Encounter but many have mentioned Atlantis. Good Luck but no matter what, you will have a great time (after all....you are on a cruise)!!!