Count me in for 2011! My FI and I just came back from a site visit through Playa del Carmen and Cozumel. We stayed at the Riu Palace Mexico (nice AI, but we want a ceremony near the water but not on sand, and their plaza is nowhere near the beach) and visited the RPRM (better food, beach is a lot closer than at the Mexico, and the gazebo has a good view of the water).
We took a taxi to Puerto Aventuras and got daypasses to the Catalonia Riviera Maya (again, nice AI, okay food, but could not find a good non-sand locale to have the ceremony) and toured Dreams Puerto Aventuras (lovely gazebo and just-in-case-it-rains venues, didn't get to try the food though).
We then stayed at the Occidental Grand Cozumel and visited Mr. Sancho's Beach Club/Wedding Garden (more private since it's slightly away from the beach club), but I got waaay too many mosquito bites on the island and my immune system overreacts to bug bites (totally red and swollen, I'm still nursing a few and I've been back for a few days!) - don't want that on wedding pictures!
We are thinking this time next year (April/May) and have narrowed it to the Riu Palace Riviera Maya and Dreams Puerto Aventuras. Hopefully we can decide on a place soon to book a date.