We cruised on the Sun over Thanksgiving week and had a great time. We didn't book any excursions for Grand Cayman or Hondurus. In grand cayman we went on the semi submersible, which is 30 feet from the dock. We saved $20 by just walking over and buying the tickets. It was nice.
In hondurus we rented a scooter and went around the island. Very nice. A little bit dangerous though on those roads. I would recommend hiring a taxi to take you around. They also have a canopy trip there that I would have done, had I known about it before hand.
In Belize we did the cave tubing/ziplining tour. This was the highlight of our trip.
In Cozumel we did the ATV beach trip. This was very fun.
Have a great time.