You may have already picked a resort but I've been to all of those and Dreams Riviera is my favorite. It is just stunning. We were able to swim in the ocean, maybe a little rocky in areas but not in all areas, most areas actually. Some seaweed comes up on the beach, depending on the weather but they are very good at cleaning it up. Their wedding department is amazing and the do offer a free wedding program. And the Wedding Gazebo is very "south pacific" looking - just beautiful! Good luck! I'm sure whichever one you choose, it will be spectacular!
