Twelve years ago I visited the Yucatan and stayed in Playa Del Carmen. It was a nice quiet place with only one proper road and no bank. I liked it there, but it was obviously growing quickly and I though that if I returned I'd probably stay at Tulum, about 50 miles down the coast, which was even quieter, and only had a few Cabañas on the beach.
We came through Playa when we arrived and I was amazed. I knew it had grown, but it took us about ten minutes to get from the highway to the bus station. The whole coast from Cancun south was being developed and when we got to Tulum it was bigger than Playa had been when I was last there.
Tulum is a confusing place to stay. Most of the hotels are on the beach, stretched out along the coast road over miles and only have power for a few hours a day, if at all. The ruins are at one end of the coast road, but there are only a few really cheap Cabañas near them. Tulum pueblo is inland, and south of the ruins. It's too far to walk from the town to the beach or the ruins, so you have a choice of staying on the beach (mostly (very) expensive, sandy, mosquitoes, limited or no power) or in town. There are Taxis or collectivos running all the time, and prices are fixed so it's not really a problem getting around.
We were booked into El Crucero for the first few nights. It's by the junction at the entrance to the ruins. We arrived quite late at night and were put into the wrong room, which was disappointing, but we were tired and thought we'd sort it out in the morning.
The next day we changed to our booked room, which was much nicer. We enjoyed our stay at El Crucero, the staff were all really friendly and helpful. The only problem for us was the noise of traffic, as it is right next to Highway 307, which has some heavy truck traffic traveling on it at night.
After a few days in Tulum we headed off to Valladolid.
We planned on staying at El Crucero when we returned to Tulum, but they were full, so we ended up staying in town at "Haz de Luz"; a place we heard about from some people on the bus from Flores.
Haz de Luz was really nice; it has four Cabañas in a garden compound with a locked entrance. The Cabañas look traditional from the outside, but are spacious and clean (the Italian owner said "Mexican outside, Italian inside") and have bathroom, cable TV and kitchen. We were paying 400 a night for two - expensive for most of Mexico, but a bargain for Tulum considering hostel beds were 210 for a double. I don't think there is a website, but it's located by the two blocks down from the bus station, and two blocks away from the main street ( by Acuario Norte and Orion).