When I had my Grandkids into the trailer for the first time, they were running each other over to get into the bunks. I have two that are 34" W x 76" long. Gkids were 12 and 8 at the time.
There is a lot to be said about using a tent for the kids. Typically, they love having their own space and away from the 'rents. A tent will also keep the clutter down. Only downside is supplying sleeping bags and pads. If I had to do it again, I'd buy the interlocking gym type pads and build a floor in the tent--no sleeping pads needed and more comfort for the kids.