Larry Gude said:
...who's been? Tell us all about it!
We're looking at late December/early January...
You should definitely go, I think you will have an amazing time. I don't know anything about Cozumel but Cancun and the waters there are wonderful.
Hubby and I went last month and stayed at an all inclusive resort a few minutes from Tulum. It was a very small resort (only 112 rooms) but you really got a feel for the culture. Plus we had a room right on the beach with a swimming pool about 5 steps from our patio and only about 30 steps to the water. There were never more than 15-20 people on our private section of the beach and the driving/snorkeling shop down the road would bring their customers to snorkel in front of our resort. Since we had never been out of the country before it was like a surreal dream with the beautiful green/blue clear water and the white sand. We both just loved it and talked about going back next year.
The snorkeling was amazing, neither of us had ever been. I saw thousands of fish and even a stingray and a turtle. I was in awe at how wonderful it was to be swimming right with nature. I went snorkeling just about everyday and always saw something new.
We went to the Tulum Ruins one day too and it was just breath taking. We also went to Xcaret but I heard people say they liked Xel-Ha better. In all honesty I think I would have rather just stayed on our beach and enjoyed the sun and water with my pina coladas.
I guess it depends on what you're into but I think you can find something for everyone there from adventure to just laid back true relaxation. It was like time stopped while we were there, a week seemed like two.