Before we had kids, (before i got married) my family and I would always go jan/feb timeframe. we stayed at the Royal Myan, Royal carribean, and the Royal Sands. My grandparents now own time shares at all three.
The resorts had great food, good accomidations, lots of packages, and all were beachfront property. Bonus if you were staying at one Royal you can go to all the Royals. There was ceramic painting at all of them so you can go an paint something and pay for what you painted and then they would glaze and accent it for you. I have lots of little bolws and turtle dishes, some fish, a sun that hangs on the patio *after almost 10 years* it still looks great.
There are also great things close to the resorts, like nice resturants and dive shops, tour boats (tours can be set up through the resort, and sometimes were cheaper that way)
We also did alot of the aniect tours, we went to Xkatra(ish-ka-tera),(spelling might be off) The Mayan temples, Xelha (shell-ha) I had a great time, every year and looked forward to the next year. We are planning one for 2010, and we will be taking the boys to that one. I just want them to be old enough where I can enjoy it as much as they do.