Hi bomberchamp, I haven't done the Riviera cruise, but love the Caribbean side. I don't know if the snorkeling is as good on that side, but it is fantastic on the Caribbean side. Another really fantastic excursion were the ruins. We visited the Tulum ruins when we went to Coumel. A visit to the ruins would be enjoyed by your children, plenty of climbing and walking. Another fantastic excursion is a swim with the dolphins. We did ours in Cozumel as well. It has to be one of the most awesome experiences in my life. They are totally amazing creatures, so strong yet so gentle. What a wonderful present for your daughter's 16th birthday. Do y'all want to adopt me?