I agree with Penny. The Falls is tons of fun but very cold water. My husband and I went to the same places you are going when we went on our 1st cruise. The excursion we did were:
Grand Cayman - Swim with Stingrays and the Hell City tour.
Jamaica - The Falls and Ski Lift tour over the rainforest. There's a restaurant up the mountain for lunch which was great but coke refills weren't free.
Enjoy your trip Tinkerbek. You'll love cruising so much you'll want to go again (like us).
Carnival Triumph - 5/12/2009