Warning: if you go to Playa Del Carmen you will fall in love with the place and become addicted - you've been warned.. To compare the two, I would say Cancun is the America and PDC is the Canada. Both great places but just that one is "busier" than the other. PDC is more laid back. The place rolls up around 1am except a couple of clubs and all night eateries. The beaches are amazing, don't let anyone tell you different. And there are some great beach bars/clubs to hang out at during the day. Restaurants are fabulous! Lots to choose from. I would recommend you try to get one of the 4-5 RIU properties that are very close to PDC. They are all 5* and 3mins away from town. AND, you can go to all the RIU properties and they are all close together. I did that a few years ago and loved it! But mostly I jump on a flight and scoop a motel room when I get there. Yes it's that easy, trust me. The buses are around 90 (i think) pesos to Cancun and the same back. The bus station in directly on 5th Ave (main drag) I sure hope you go..you will absolutely love it. If you hit the "Bucket" say hi t Big Al for me. Cheers and good luck on your vacation!
Try Playa for sure....it was a real fishing village before Cancun was even a thought......Rember that when they started "building" Cancun 30+ years ago, it only had 7-10 people living there.....check out these forums for more information http://intheroo.com/ or http://www.playa.info/index.html and definitely buy a map from this wonderful couple..... http://www.cancunmap.com/ Have a great trip!
The Playa del Carmen area offers a different side of Cancun. The resorts are much larger and there seems to much more shopping IMO, there is also more to do in the area as far as diving, snorkeling and places to visit. The one thing I like about Cancun vs Playa is the water, the water in Cancun is so much nicer as well as the beach sand. Cancun also has better public transportation and better night clubs, but I think that in the next few years that will all change. I did hear rumors that they are building a new airport in Rivera Maya area, I was told this by one of our tour guides last year and if this is the case there is going to be a new building boom in that area. I prefer myself to stay in the Playa Del Carmen area because I stayed at a few resorts in the Puerto Morels area and you had to take a cab to get out for the day and it was like $22 each way to playa and something like $40 or $50 to Cancun. It is so much nicer to just be able to walk down town.