From what some people are posting, it sounds like we should stay on the ship during the port days. Is it not worth it to do any of the excursions, or not safe to walk around? For us who've never been on the Western Caribbean cruise before, or any cruise for that matter, I'm getting the feeling that no one is too excited to visit these ports. As first timers, we're pretty darn excited to be going! Has anyone done any excursions that they enjoyed, or can recommend? (Or definitely not do?!) There are just so many of them!
The only time I stayed on the ship rather than go into town was on my 4th visit to Nassau. I like visiting ports (even Mexico!), and have enjoyed Cozumel (ship tour to San Gervasio Mayan ruins - with plans to go to Tulum on the Magic) and Grand Cayman (Stingray and Island tour with Native Way Watersports: http://www.nativewaywatersports.com/). I have read Jamaica has its safety issues, so I would tour there with a group (ship tour or private) and not wander on your own.
Check out the Caribbean Ports of Call forums on Cruise Critic for help with each port: http://boards.cruisecritic.com/forumdisplay.php?f=587