Class A with the most living space (under 30 feet)

You now have three kids and their stuff to deal with as well as holding tank needs for 5 people unless you only stay where there is sewer. You might want to look at some units with bunk beds so most everyone has their own bed versus using the dinette / sofa.

I have not seen one, but Winnebago has a new Vista with larger tanks and bunk beds in the 32 ft range. It's on their website and is the 31BE.