Thanks Dave for the quick response. We are looking to do a lot of snorkeling and other water activities. Is Xcaret more commercialized, (just what I've gathered from their web-site)?
They have gone to great lengths to make Xcaret appear as natural as possible and they strive to keep it ecologically sound. But it is mostly artificial.
Definatley do Xel-Ha!! It is beautiful, the snorkeling is amazing. If you have time try to do the lazy river too, and then head down to see the tuna at the entrance to the lagoon. Have a great time!