We are leaving in a week to go down, we have a large party (73 people) and the majority are all in our 20s. I will let you know on the rowdiness or lack of it when Im back at the end of April. We chose this resort because it was a smaller resort, not as many weddings and the wedding planner is AMAZING!!!! There was nothing but great things said about Maria (who is no longer there) and Lupita which made me really comfortable with all the planning. And the pictures I have seen of the beach set up is beautiful, I fell in love lol You can do a private reception, I cant remember the prices (it is extra) you can email Lupita and she would let you know. We are just going to go to the disco after our reception as we didnt feel we needed to pay extra for a private one. It worked better for our budget.
Hope some of this helps! I will do a review when we are back with lots of details Good luck with the planning