Wow. A poster actually asking what is appropriate for the culture! Would that all visitors did!
Punta Cana, for the most part, is comprised of all-inclusive hotels where most people don't leave the resort. If you are looking for areas to mix and mingle a little more with local people (Dominicans and Expats), may I suggest Sosua or Cabarete?
You will still have the tourist/local dynamic, but that's to be expected on a trip where you likely spent the equivalent of 6 or seven month's local minimum wage for your one week trip. There are a lot of interesting characters hanging about, and yes, a few douchebags. It's just that here the you're more likely to run into the douchebags because they will actively seek you out.
Enjoy the trip, enjoy the people, but take what you're told with a grain of salt. And that not only from the Dominicans but from the expats as well (many of whom will be more than happy to bend your ear with tales of how lazy Dominicans are while drinking their fourth beer on a Tuesday at 2PM at the local pub while those same 'lazy' Dominicans are at work)