Cancun is a great place to spend your vacation, its near to wonderful, beautiful places, such one of the new 7 wonders of the world, yep I'm talking about chichen itza, you can go there and the have a nice yucatecan dinner, relleno negro, frijol con puerco, queso relleno, those are delicious and you will never forget it, of course there is another colonial city, merida the capital of the state of yucatan, as a personal suggestion visitor in Cancun should spend 2 or 3 nights there.
Rent a jeep for several days or a week, however long you are there. It's cheaper than the taxis. Take a trip around the back of the island. Stay away from the west side day clubs. go to the Celerian light house. Eat dinner at Casa Mission resturante. anachesbbeachesbars.an.bbeachesbeaches