We just returned from the Bahia Principe which is just south of Puerto Aventuras. If you like to snorkel, you would probably love Xel-Ha which is quite close to Peurto Aventuras (probably $10 by taxi or $2 by collectivo). We actually did a 1 day trip that included Xel-Ha and the ruins at Tulum.
We also loved the ATV tour (1/2 day) which included a trip to a cenote (underwater cavern with spring water) which also had pretty cool snorkeling and a visit to a Mayan area with snakes, tarantulas and monkeys (all of which you can hold if you dare!).
A trip into Play Del Carmen would also fit the bill for you - shopping and great bars and I'm assuming dancing. Playa Del Carmen is also a close taxi or collectivo ride from Puerto Adventuras.
Deep sea fishing is also available right in Puerto Adventuras if you're into that. Some of the people in our group went and caught lots of fish.
Lots of people rave about the Jeep jungle tours in the area so you might want to look into that as well.
There are lots of fun day trips to try in the area. It was tough to decide what to choose with only one week!
Have a great time!!