I recommend the dos ojos main shop. There is a shop run by americans, not that it makes any difference. The main reason i recommend them is that I got back into diving in November 2004 with a refresher coarse from them, after being certified in May 1987. I only had my certification dives between 1987 and 2004, primarily kept out of diving due to budgetary issues.
I was pleaseantly satisfied with their no hassle, to the point, safety first attitude along with a fairly comprehensive refresher coarse for open water and the overhead environments. I also got in a two tank dive and a wonderful experience through the Dos Ojos cenote.
The shop has makeshift truck transportation on the property, so you will not have to walk the couple mile hike from the shop to the cenote. You will, however, have to climb down about 20 to 30 feet of steep steps to get to and from a deck where you ultimately set up you gear and get in the water.
You could save on money by taking a bus there, and save more on getting picked up by one of the many white passenger vans that run along the coast to and from Playa del Carmen. I ended up taking the greyhound style autobus from playe del carmen, and got dropped off a few blocks north of dos ojos, due to the bus company not having a clear understanding of the town or destination near dos ojos. But the walk was not that bad. On the way back, I got picked up by a passing white passenger van for about 20 pesos ($2).
Whatever shop you plan to dive with, I am sure you will have a good time. I am not sure if you pay more with a shop that is based out of Plays Del Carmen or if you deal directly with the on site shop at the cenotes?
Have fun!!
