Just in my opinion with kids ages 8 and 5, I would go to the turtle farm in the Caymans - they will just awwww over all the turtles! In Cozumel I would head over to chankaubab (however I have not been there since the hurricane) because they have dolphins, sea lions, snorkeling, and just an all around good time for a 10.00 admission fee (unless it went up). In Jamaica -- don't go out on your own - go on an excursion - perhaps dunns falls they may enjoy! Enjoy!!!