I know I'm a bit late but guess what? I've stayed at The Royal Cancun.
My FI and I went in 2008 and LOVED it! He is a very picky person and had a wonderful time! It is awesome because the back of the hotel is where the new expanded beach is. That's where you can go to lounge around. The front of the hotel is a regular city street. Your guests who want to be able to go into town to party can hope a bus right there and take it into town. If you ask me, that's the best of both worlds. The Cancun location is so beautiful, the rooms and the ceiling fans are to die for. It really is a nice place! We absolutely loved the resort so much so that we are getting married at The Royal Playa del Carmen. In addition to being a Royal brand, we loved that guests who wanted to party would have easy access and guests who wanted to chill could do just that.
The naysayers are just that-naysayers. Remember that this is your wedding and you should be planning it the way you want. I PROMISE YOU that those who have something slick to say will definitely be eating their words!