Hi dhoemann, welcome to Cruise-Chat. We did ours in Cozumel and it was fantastic. They took us to Chankanaab Park and we spent over an hour in the water with the dolphins. No matter where you do it, it is an awesome experience. You might want to do Calica instead as there are so many things to do in Cozumel, but if you're like most of us on this board, you'll be back to Cozumel many times
Best wishes for a fantastic cruise, and once again, welcome aboard!