When you are in the Quintana Roo area, there are many places to eat, have drinks, and shop! Playa del Carmen, has a street called La Quinta (5th Ave.) where every single establishment is cooler than the other. Anything from traditional mexican food, to high en steak houses are in this area.
These are some of my favorite spots:
The Cigar Stores, where freshly hand rolled cigars are sold. You can see step by step how cigars are made and you can choose from a wide variety of flavors and sizes.
In la Quinta and La Calle de los Corazones you can find Sur Steak House, a traditional Argentinian restaurant with an amazing seasoning! The cuts of meat are amazing, the portions are generous and the mixed drinks out of this world... The staff is very nice, the prices a little higher than your more local cuisine, but it is worth it!
In this busy streets you will also find live music, from 8 men mariachi bands to elderly "marimba" players, that will entertain you for a tip, just beware of your belongings, as anywhere in latin america pick pocketers are everywhere.
You will also see a lot of rolling kiosks, that sell all sort of pastries, fruits and juices. As a person that lives in the U.S., I would advise you not to try them.. The water and health standards are not the same in that part of the continent... Always drink bottled water and avoid ice if possible, specially those giant chunks, which are clearly homemade with tab water.
What I will suggest you to do is walk pass the chapel in the middle of the park, and head towards the beach, where you will easily see a bar ON the beach, very traditional, circular bar with stools planted on the ground! But the biggest and best margaritas ever! delish! And very generous with their alcohol pours...