WE stayed at the Bahia Principe, I think it was the Akumel side for a friend's wedding almost 2 years ago.
We went to Xel-Ha, similar to Xcaret, and we thought it was really nice-great snorkelling, and we swam with the dolphins while we were there, which was a wonderful experience-although you can't help but feel a little sorry for them being 'penned' up-however, if they weren't, we would not have been able to swim with them. We went with a group of people and some of us went on the longer swim, which the dolphins push you along with their nose and the smaller one you get to swim with them and touch them.
We did a tour to the Coba ruins, which was amazing, included in this trip was a rappel, zipline, lunch prepared by some locals, and a trek through the 'rainforest', which had us in a canoe, a bit of a hike then we swam in a cenote, I can not remember the company's name now, but the hotel offered the same tour, we had booked it online before we arrived. It was an unbelievable day, our guide was Emilio-he was fantastic!
They have their own 'mall' which we found to be cheaper for most things than shopping in Playa Del Carmen, which was about 20-30 min cab ride, if I remember correctly. Playa was nice.
There is also an 'animal' sanctuary, i guess with caves almost right across from Bahia Principe, which was very interesting. I had a monkey come right up to me as we were waiting for the tour to start and it played with me for about 5 mins, which was pretty fun!! The caves were very interesting, there are bats in them, but they never bothered us.