I think it depends on what you are looking for during your vacation.
Personally, I have no interest in the actual 'strip' of Cancun. All the resort-bar hopping and shopping are not what we are looking for.
I have been researching our 'one of these days' trip to Mexico, as it is next on our travel list, and I have definitely decided on the Playa/Riviera Maya area. The mayan ruins and other natural attractions are all located south of Cancun as well.
For some people, the glitz and crowds and non-stop activity of the Cancun strip are just what they find exciting!!! But, for us, not so much.
I just love tripadvisor for info, traveler reviews, and even tons of traveler photos... (the button for traveler photos will show up once you click to read some full traveler reviews)
You can narrow your search from this entire area down to very specific locations, such as the Cancun strip, Playa Del Carmen, Maroma beach, Puerta Aventurous, etc...
Happy planning!