i suggest you leave cancun and head south to playa del carmen or tulum. you should experience a little bit of Mexico since you'll be in the region.
Coco Bongo...Daddy Rocks...Senor Frogs...Carlos N Charlies...in that order were my favorite clubs/bars Be careful and don't let anyone shake your head and blow a whistle in your ear while your taking a shot!
IMO, it really depends on how old you are. If you're young, Cancun can be an extremely fun place to be w/ all the clubs and everything. But if you're older and looking for a relaxing vacation, there are a ton of places better suited for that.