Hi
Looking at the layouts and bed sizes, for a family of 3 I'd head for the 540 or a 550 without the fixed bed. The convertible dinette on the 550 is not as long as it really needs to be if you have tall children/young adults. For 4 persons the 550 with a fixed bed gives very little elbow room when seated if you need to eat in the van due to nasty weather the double dinette version gives two seating areas the adults can have one end and the youngers the other.
The 530 is not really suitable for a family of 4 unless you can either get a set of bunks in the front or someone is prepared to sleep outside in a pup tent or awning.
The only Touring with real ability to sleep 4 adult sized folk is the 418 but it does not have a washroom.
Denise & Phil