Buy a Can Do map of Cancun before you go and spend some time (maybe on the plane) aquainting yourself with all of it's useful tips. http://www.cancunmap.com/ It is so much more than just a map.
Even if you are staying at an All Inclusive resort (meals and beverages included), try to take at least one night to go out to dinner at one of Cancun's wonderful restaurants. There are more than 300+ establishments to choose from, including Mexican, seafood, Argentine/steak, Italian, Japanese, Chinese, etc., etc; in other words there's a little something for everyone. 212eric
Experience some Mexican history. Visit at least one "ruins" or Zona Archeologico. Chichen Itza is the most populat. Tulum is the closest, but much smaller. Coba has the tallest strucutre/pyramid. Ek Balam is my favorite as they are still excavating, and its tallest building is taller than El Castillo in Chichen Itza. Hire a guide when you get there. Otherwise you will be looking at a pile of rocks, figuratively speaking of course. Negotiate for a price you are willing to pay.
Purchase (and use) an Entertainment Plus Card. You can get special deals on restuarants, tours, and other money saving deals.
STREET MEAT Eat some "street meat" down town. It never killed anyone. That would be tacos, burritos, etc. or whatever, at Parque las Palapas, in front of the bus station, across the street from Chedraui as you enter town and at many other places where tourists dare not roam. In addition to "meat" you can get Marquesitas, which are like crispy rolled up crepes that are sweet tasting with some cheese inside. Elote, which is corn on the cob, on a stick, complete with a bit of spicy chili powder, mayo, cheese and salt and pepper. Esquite (not sure of the spelling) corn that is cut off the cob and served in a styrofoam cup, with lots of lemon and mayo and of course the hot sauce.
Don't over schedule, make sure to plan just some beach/pool days. You won't be able to see and do everythng in one week, you'll have to come back over and over to see it all!
