It is a nice area.
I've only been the once, but we went to:
Xel Ha - ecological park where you can drift down the river looking at the fish and turtle.
Xcaret - ecological park crossed with a theme park - no fairground rides though not that sort of theme park.

Chichen Itza - now one of the new seven wonders of the world.

Also in the area is the "island of women" (forgot the real name) and Cozumel.
At certain times of the year you can go out on a boat and swim with Whale Sharks. If it is something you would like to do, you can time your visit to coincide.

I always point people to the Caribbean Warehouse site where they have some nice pictures of the many hotels in the area!. They also offered me great advice on the phone even though I changed countries over the days, and when I did book with them, I actually saved noticable money as well, which I was not expecting.

*Edit. Post removed. Please do not spam the forum. Pippy*