Our trip to Cancun was about evenly divided between two sorts of days. We spent three relaxing days sitting in recliners by the pool on the beach, jogging on the trail adjacent to our hotel, walking on the beach and snorkeling, and eating leisurely meals in very nice restaurants.
We spent three interesting days on tour. One was the trip to Isla Mujeres via cab, ferry boat, and rented golf cart. We spent two full days on organized bus tours. One was to Coba and a nearby Mayan village, and one to Chichen Itza and a nearby cenote.
Both bus tours included stops for lunch and visits to curio shops. Our only purchase was two clay masks, which we bought near Coba. The Chichen Itza guide made it almost mandatory to buy a silver or gold necklace with "hieroglyphics" that represented a name or a date of one's choice -- priced by number of letters. He also tried to sell us a bottle of tequila with our photo pasted on it. We resisted the pressure, but noted that most of our fellow tourists bought what they were told to buy. Tour bus tours have pros and cons. We really didn't want to drive for many hours -- a bus that showed videos during the many hours of travel was an overwhelming pro!
To read more about our trip to Cancun you can check my food blog posts: Maya food and plants and Restaurants in and near Cancun and to see about the Mayan village near Coba, my story blog post: Maya Children.