
Rio Lagartos
It’s a little far, about 150 KM from Cancun, but it’s something I would recommend.
Not only you will see the beauty of hundreds of flamingos flying over the waters, but you will face a sanctuary of wildlife and marvelous sights. And it will be easy to add the visit to the mandatory trip to Chichen Itza.
Merida

It is not a “must see”, but the capital of Yucatan deserves a visit.
Furthermore, Mérida is a good place to stay while visiting Uxmal or Dzibilchaltun
Uxmal

It is a very long trip, but it surely deserves to be done – the ruins, the jungle, the ambiance is something that I will never forget.
It is possible to do it in a single day, but it will be a very hard day, so I suggest a overnight trip.
Details of the site may be seen in my Mexico page
Dolphin Promises

When we arrived we were told that, in the early morning it was common to see some dolphins near the hotel.
Jet-lag made me awake around 4 AM in the first days, and I took advantage of it to go and see the sunrise, waiting for the dolphins.
They never showed up, and the only consolation I had was being the first to dive in the pool, on a marvelous 6 AM swim.
Live music

One thing that I appreciated in Mexico was the presence of music and dancing everywhere. Of course we were tourists, in the touristy circuits, and music is something easy to sell to tourists, but, I think that it’s possible to feel the difference between dancing for commercial purposes and dancing with pleasure, even in a professional context.
I felt it in Mexico, real pleasure in the permanent music and dancing, and a high level of quality.
The shows in our Hotel, Kristal, were really great