I'm going to Tulum with a group of friends--some think we should rent a car from Cancun, others think taxis are the way to go. We're staying for a week and want to spend a good amount of time on the beach. Any input on cost, convenience, etc?

Tuffi,

When I go I usually rent a car. An economy car will not cost you that much and in my opinion the freedom is worth the little extra cost. There are a number of places up and down the "Tulum Hotel Zone" worth exploring and you can get to restauants etc. FYI...a taxi ride to Tulum is not cheap...but if you have a small group it might not be to bad.

Also, in the last year or two there have been a couple places I believe where you can rent a car in Tulum...perhaps even some of the hotels have cars to rent too...?

or you can book you a car/van service,that takes you from the airport and then rent a car in Tulum for the days you want to spend out of the beach, for the airport transportation you can try http://www.tucankin.com, in Tulum you can find Executive or Hertz rentals.