We stay at the Iberostar Tucan/Quetzal in the gated Playacar community just 5 min south of PDC. Beautiful jungle setting situated on a gorgeous beach within minutes of town and attractions and a very safe, quiet area. The complex is gated, and the resort is guarded so you feel very safe there evenings. And the jungle paths at night are magical. We haven't tried anyplace else because we love it there so much. Also great staff and entertainment and food.

We sometimes stay in Cancun after our PDC visit to be closer to the airport and for a more cosmopolitan experience in the hotel zone. There we enjoy the RIU Palace Las Americas and the RIU Cancun next door.
But Cancun doesn't compare to the Mayan Riviera for natural beauty. We would visit Cozumel and drive the island, but Playa Del Carmen and the Riviera Maya coast is our preferred area. Just gorgeous beaches, friendly people, and beautiful natural attractions and ruins.

Trying to do both Cozumel and Cancun or Cozumel and Playacar is a bit much and you don't get enough time relax and enjoy one area. But a day ferry to Cozumel is plenty as you can rent a car cheap and drive the island and see the beaches. We visited the Iberostar there and although it's neat it's not as nice as the Tucan in Playacar. Very quiet there and not the entertainment that the Tucan offers.
Take a look at the Tucan, there's a site that has pics, videos, and reviews, I believe it's www.ib-board.com/boards/index.php/index.php, just select the link and scroll down to the Ibero resort you want to look at.