We stayed in Villa Carambola at Villas Solar. Very nice place... beautiful teak construction, nice little kitchen, and great patio for lounging/napping. We stayed for two weeks just for surfing. The place is a few minute walk to the beach break at Playa Santa Teresa and walkable to surf Playa Carmen. Walkable to several good restaurants.
Greg, the owner, is super friendly and has the lowdown on good places to eat, surf, rent quads, get tours, etc. The caretakers Elisa and Chino are very friendly, but I don't speak much Spanish so unfortunately didn't get to know them well. Their dog Luna is super friendly.
I would recommend Villas Solar. They are a great value. The only downside I found was that the main road through Santa Teresa is nearby and it is noisy. I'll point out that at night with the A/C you can shut the windows to block some noise.
I'll also mention that VRBO is a little strange... when you book, you have to make two payments: one to VRBO for their listing service, and one to Greg for a deposit. I promise Greg isn't trying to rip you off.