Greg and I are currently waiting until next month (or so) when the flight schedules post for September (Currently they show to the beginning of August). We will pick our dates based upon the cheaper days to fly. In the calendar tab you can view the dates that Chris and Stef are getting there as well as Stef's family. (Chris and Stef have to be there 3 business days before the wedding to be able to get married there).
We plan to be using Southwest points so we will be flying Southwest/AirTran. There are no longer flights from Denver to Punta Cana (Can't even connect anywhere from Denver) so we will have to fly from Denver to somewhere (may be Atlanta/Ft Lauderdale/Chicago as those are the cities that then fly direct to Punta Cana). We will probably fly in a day ahead of whenever our flight to Punta Cana is so that we aren't risking any delays or cancellations that would cause us to miss our Punta Cana flight.
As Stef has indicated, booking directly through the resorts website using a AAA discount may be the best way to go. You can also use a military discount or AARP. If you don't have a AAA discount it's pretty cheap to get one so you may want to consider doing that to save the money on this trip. I may inquire directly with AAA so I can see what their travel insurance looks like although booking directly with them doesn't usually get us any additional discount.
That's about all I know right now... Probably more in a few months.