We bought a sterling van with large rear bathroom and seperate shower in 2003,this worked quite well with our 10yr old son who slept in the side dinnette bunk,then we had our daughter and it was difficult to get her settled at night in the side bunks with the tv on or us chatting,especially if we had friends caravaning with us.Also we never used the shower.
We decided to change to a 5 berth layout and bought a Eldiss Avante before we went to France last july,it works far better for us my daughter goes to bed at the same'ish time as she does at home and we can shut the door to the end bedroom knowing she won't be disturbed,so we can relax more.And we have a side bathroom which is more than adequate,Hope this helps you make a decision Andrew.