Nice day trip
Tulum is a short day trip away from Cancun, and well worth the drive (or tour if you want). The Mayan ruins here are terrific, but only accessible from behind a rope for the more interesting portions. While it's unfortunate, it's also necessary to ensure that the ruins are here for more generations. That being said, there are still some places where you can stand in a 'room' or climb though some passageways and experience the ancient world up close and personal.
There is a wagon service from the 'cultural strip mall tourist trap' that is the entrance to the park. What I was not keen on was the way in which the pricing worked. First, you pay for parking. The next booth (past the 'mall') is for the wagon ride to the ruins themselves (about a half mile away), but you are welcome to walk (though this is not obvious). Once you get to the ruins, you then have to pay the entrance fee. Overall, I would have preferred to pay all of these fees at the parking lot, but I can see where the a la cart method may be preferable to some.
Tourguides are extra. I've heard mention of a camera fee, but because mine was in my purse, I didn't actually encounter anyone charging for that. I wandered around at my own pace. Signs were in English, Spanish and another language I cannot place (Mayan).
I would go again with someone who had not been there, but I would more than likely head somewhere I had not been before if I were on my own.