kilmca,
We just put down payment on airline tickets for Cozumel, but not until March. Definitely a diving trip. We're planning on doing minimally 3 dives/day...can't wait.
Also, Plasa Las Glorias right in San Miguel has a really great snorkeling area, open to anyone right behind the hotel. Before we were divers, we did some night snorkeling there, and you would NOT believe the wildlife that came out...really awesome. Octopus, squid, stars, flounders, etc., etc.
We love Cozumel, this will be our 4th trip there, and every time is different, but always great.
Lisa :happyfish