The first time we went to the Mayan we did Xel-Ha and the Tulum ruins tour (half day each). Wished we would have just gone on your own. You can take the colectivo (Van-Bus) from the Main Road. Its cheap cheap. Buck or so for a spot in a van with 10+ other tourists/locals and (a chicken or two if you are lucky
) Believe they run every 15 minutes back and forth between Cancun and Tulum. You also aren't tied down if you want to spend more time or less time at a certain place.
Colectivo
Sounds like you will be hitting the Tulum ruins. There is a nice cove at the bottom of the cliffs. Take some towels so you can go for a dip.
Also take some banana with you from breakfast and go snorkel with the fishes just off the beach of your resort. Its awesome having them eat out of your hand. Just don't be douche and leave the peel floating in the ocean.
