The dancefloor will not fit where the tables & chairs are located in the Chillout - what they did for us was set it up in front of the club. You probably can't see it in our photos because of the angles they are taken on, but if you check out the photo of the front of the Chill Out you can get an idea of how it might look (and they actually dug into the sand so that the dancefloor was level with the ground - which I loved). Additional, more casual seating was provided around the dancefloor for those who needed a break.
I read through the other posts and noticed that you are considering the Sunset Gazebo. It is definitely more private than the Grand Riviera Gazebo and an added bonus, if you book the Chill Out, is that it is actually located right next door.