My wife and I stayed at the El Dorado Royale in Riviera Maya. Adults only resort, several restaurants to choose from that were really good for an all-inclusive place. The service was also top notch. The beach wasn't all that great, but I don't like sand or saltwater, so I stayed near the pools which there are several to choose from. If you get a casita, you basically have your own pool outside your door with your own waiter.
They also have a top-shelf martini bar that they don't really advertise where you can get good liquor and drinks that's still free.