I am just back from a trip to Mexico with my wife, and since we used the Mexico Chowhound site to plan many of our meals, I just wanted to report back on where we wound up. I have a separate posting for Merida, but here are my notes from Playa del Carmen-
I'd like to start by saying that, wow, Playa has way better food than any beach resort has any right to have! By straying just a little west of Avenida 5, we found some of the best Mexican food we've had anywhere. And so all due respect to the many no doubt excellent places on 5th, I'd like to strongly recommend the following places:
> CH Super Carnes -- this fun place is located in a residential neighborhood off Calle 1 South roughly in the Avenida 20-30 range. It's a longish walk from the beach, but doable, or a short cab ride. Super Carnes is a combination meat market and parrilla, so you know the meat's good. You order from maybe a dozen options, and platters arrive loaded with grilled meat and the usual sides (avocados, grilled onions, salsas, etc.) and a big stack of fresh tortillas (there's a tortilleria across the street). You sit pretty much on the sidewalk, as the tables sort of spill out of the meat market in the back. The food was outstanding and fairly cheap (< $15 for enough food to stuff both of us). And why are the avocados so damn good in Mexico?
> Carboncitos -- this places is between Avenida 5 and Avenida 10 (consecutive blocks in PDC's wierd street numbering system), maybe in the Calle 8-10 North area. It's a big place, but you can just sit out on the sidewalk and ignore the full service restaurant behind. It's open late, and we were just there for a snack (we were full from CH Super Carnes a few hours before!). We had several of the tacos al pastor, which are small but shockingly delicious. So we ordered more...and more...and more...we couldn't get enough because they were so awesome! But anyway, it's all we had. They're like $0.75!
> Dr. Tacos -- this place is widely known among tourists, but good nonetheless. It occupies a tiny space on Avenida 10 at roughly 12th-14th Calle. Basically, they have like 5-6 fishes (octopus, shrimp, squid, etc.) and chicken -- and you can get it grilled or fried -- and it comes out on a tortilla...and that's about it. But where the magic happens is the well-appointed salsa and pickled vegetable bar, which makes the tacos awesome. We ate here twice it was so good. The owner is also super friendly.
> El Fogoncito -- We had actually planned to go to Cactus for a "fancy" meal, but it was empty and had a bad vibe, so on the way back to the beach we passed this place and it was jam packed, so we checked it out. It's right off Avenida 30 in (I think) the 20s range -- across from the humoungous Mega supermarket. Like Super Carnes, it's open and spills out into the sidewalk and street, and like Super Carnes, the focus is on the grilled meats. They also have an awesome Queso Fundido with Chorizo -- heart stopping yummy. This place is maybe 30% tourist / 70% local. Crazy and loud and fun, highly recommended.
I have some pictures on my blog: