Good for you <img src="http://www.traveltalkonline.com/forums/images/graemlins/Clapping.gif" alt="" />
We have had 2 trips to Playa and are in process of booking early 2017. First off, with peso running just over 18 to 1 against the dollar you will find things incredibly "cheap" unless it's a US import product. When we were last down the peso was about 14.5 to 1 and I thought it was great.
Do pay in pesos, not dollars. Get your peso's from a bank ATM not the cambios or the ATM's you see along 5th.
ScotiaBank (affiliated with Bank of America) is just up Constituentes(sp?) and a good place to get pesos. If you happen to have a BOA debit you can also save on ATM and a bit on currency exchange. There is the ADO bus service from the airport to 1st and 5th which is fairly cheap but you will have to taxi or haul luggage to your location or there are several shuttle services that will do door to door. Watch out for the taxi's, they will overcharge you every chance they can. Also, the taxi's lined up and waiting have an up-front extra charge. Taxi's are all over the place so if going very far (walking is great) get out and flag one down.
There is a very active Playa del Carment forum on TripAdvisor, check that out.
PM me if you have any more questions.
Have a great trip, hope for no sargassum on the beach.