Which hotel/resort should I stay at in Tulum, Playa del Carmen, or Cancun?

I’m going to Mexico in November for a friend's wedding. She's getting married in Tulum. She mentioned checking out hotels in Playa del Carmen. And we fly into Cancun. It's going to be a vacation for my girlfriends and myself. Where should I stay, and how much should I figure in for transportation? Would it be a better time staying in Cancun and paying for a cab to Tulum, or vice-versa? I've never been out of the country so all suggestions would be appreciated.

---

Answer:
My favorite hotel on the Yucatan peninsula is the Posada Luna del Sur in Tulum, but it is very popular and only has twelve rooms (wish it was bigger). So click the link below, then click the Posada Luna del Sur and plug in you dates and see if it's available. If not then you can check other highly rated hotels on the TripAdvisor list. I wouldn't stay in Cancun too overpriced for what you get. If you don't find anything you like in Tulum research on TripAdvisor for Playa del Carmen hotels. See the second link for a map of Playa de Carmen hotels. Links on the left also give taxi rates and getting around information. Buses and collectivos are much cheaper than taxis. You could rent a small automobile for a week for what you would pay for a taxi from Cancun to Tulum.
Where is your friend getting married? I'm researching a beach wedding for my daughter next year.