I second the Palace Resorts!
My husband and I honeymooned earlier this summer at an all inclusive called Xpu-Ha Palace Resort on the Riviera Maya (not far from the previously mentioned Moon Palace, about an hour south of Cancun) and it was INCREDIBLE!!! All of the rooms are thatch roof huts with huge private balconies, and each room has a jacuzzi in it--it was very romantic. The beach there was a white sand beach with crystal clear aqua blue water--the best I have ever been to. There weren't a lot of kids there, either.
The resort has a bunch of little special extras for honeymooners like a honeymooners cocktail, candlelight dinner, and bottle of champagne in the room for no extra cost. Not to mention room service 24 hours a day. This place was just phenomenal--so much better than other resorts in the area. You can get good rates on perx.com. I can't wait to go there again!
Congratulations on getting married!