Playa del Carmen
Our final stop was Playa del Carmen, the formerly sleepy beach village south of Cancun that used to be best known as the place you caught the ferry for Cozumel. No longer, it's a pretty nifty beach resort in its own right now, but I think much nicer and more appealing than Cancun and many of the others. If you stay in town, you are a short walk from anything -- nice beaches, good shopping, and actually some pretty amazing places to eat.
Everything happens along 5th Avenue, the pedestrian street that runs parallel to the beach. Tons of places to shop and eat or drink (although the best food is another block or two inland in the dozens of taquerias).