With kids under 10, you have a good five years of comfortable sleeping in whatever rig you choose. Also, you are allowed to get something different after a few years if you desire. Once everyone is 5' tall or more, bunk beds and dinettes can be too short, and then it's a tougher decision.
Our friends have four kids 11-17. All their trips within 3 hours of home. They got a big 5th wheel that sleeps about 8 in 4 bunks, a queen sofa sleeper and a king for mom and dad. Journey = not great. Destination = awesome.
Other friends have two adult-sized teens and a Prevost with bunks. They hate the sleeping arrangements. The kids feel like they are in coffins because the beds are so narrow and short compared to home. Journey = awesome. Destination at bedtime = not great.
