I am getting married in Cabo however I stayed at the Riu Palace Punta Cana in December 2005. It was absolutely beautiful. The grounds were not quite as full as the other resorts but it had just opened. I am sure it is more lush now.
Everyone at the resort was great. The service, food, activities, and bars were all great. You can also use the amenities at the other sister properties when you stay at the Palace. The Carribean Street Party night was cool too.
When you first walk in to the resort you will be blown away be the lobby. It is gorgeous. I did not see any weddings when I was there but the beaches and gazebo are very nice.
Let me know if you have any questions about the resort. My fiance and I had a blast!