I saw a previous poster about the Riu Palace. This hotel company is so beloved that there is an unofficial guide/ fan club to the Riu Palaces all over the place. Google it. Lots of pictures on it. Make sure you stay at the
Palace, not the other Rius. They aren't quite as nice. Official website:
www.riu.com
We stayed in Cancun at the Riu Palace Las Americas for a week for about $3000. It's all inclusive and the food was great. The style is like a giant elegant hacienda, all white. The beach area was the best we saw around there. There are two Riu Palaces in Playa Del Carmen. Maybe next time we will go there but we really liked the beach at the one in Cancun. We had such a relaxing time- it's a big honeymoon place. We went in July, which is when more internationals come than Americans. For us, that's a good thing.
We are not club hoppers but it is really close to the best nightclubs. We did a VIP trip from our hotel- it was really fun with lots of internationals staying at our hotel. We didn't have to wait in line and they had a special, good area for us to sit.