We started with a Class C and then ended up going to an A. The problem with the C was that the kids would sit at the dinette and they could not see out the front of the unit so it was very much like riding in a bus.
We consistently travel with four adults and our twins who are now 18. We will be camping this weekend with the four of us and two friends of the girls and we'll be fine on space and storage.
Our A has bunks and we can sleep 2 in the bedroom, 2 on the fold out couch with an air mattress, two in the bunks and one by knocking down the dinette table. You could sleep two on the dinette but they would have to be really good friends or small people.
A used diesel pusher with bunks can be found out there without too many problems. Berkshire, Charleston, Fleetwood, Newmar, Tiffin, and I'm sure there are others are all out there to be searched and checked out. Enjoy your search and good luck.
2011 Berkshire 390bh