@ChicoryCreek: I would highly recommend Sanctuary Cap Cana in Punta Cana, Dominican Republic! My Darling Husband and I took our honeymoon there, and it was fantastic. Not technically adult only, but there is very little for children to do there, so there were next to none when we were there.
I would go back in a heartbeat, the food was pretty great all around, they had a seafood restaurant that was open air and on stilts over the ocean! Also had an Italian restaurant, an Asian restaurant (with live hibachi cooking shows), a steakhouse and a buffet restaurant. Each night around 3 different restaurants were open, and they were typically a la carte style, but you didn’t have to make reservations like you typically do for a la cartes at all inclusive resorts.
They have a ton of different rooms to choose from, including some luxury ‘royalty’ villas. We just had the most basic room, Junior Oceanview Suite, and it was perfect for us, though we wouldn’t have turned down an upgrade!
The beach was nice, a little small and rocky, but fully functional. Right next to the resort, there is a ‘public’ beach, less than 5 minutes walk, but it’s in a gated resort community so it is very safe. It is about 1.5 kilometres (I think that might be about a mile) long, and pinkish white, soft sand.
There are 5 different pools to choose from, one with a swimup bar, which is where we spent most of our time. The resort was supposedly at full capacity while we were there, but it is laid out in such a way that it never feels overcrowded.
Good luck deciding! In case you aren’t aware of Trip Advisor, you should definitely check it out, they have tons of reviews for every resort out there. That’s primarily how I make my decisions! LOL