Staying on the ship. Yes, you can do the strw market in 2 hours or less, and the horse and carraige ride is nice (about 20 minutes, maybe?) but unless you have never been there, it isn't anything to see, and it is a lot of - Braid your hair, pretty lady? or T shirts, 3 for 10, best deal you can find (untill you go on the side alley and they are 4 for 10). And to have to book a day room at a hotel to use the beach at Atlantis? Sorry, but CC is included and so much nicer. I say this after having been to Nassau 11 or 12 times, and CC once. There are limited activites on the ship, but you can enjoy them more with fewer people. Even if there was nothing top do on the ship, I would not get off there or in Freeport.
By the way, I found the prices for liquor to be less on the ship than in Nassau, also, by at least a dollar per bottle.