Sadly, class A floorplans for families are pretty limited and there are a lot more options if you stick with towables. Nothing like describe exists - the closest you'll get would be something with 2 bunks and a drop-down bed in the front (e.g. Fleetwood Storm 32BH (
http://www.fleetwoodrv.com/storm/floorplans/32V or Thor Palazzo 33.3 (
http://palazzorv.com/floorplans.php).
If you want something driveable, you'll also find suitable for 6 in class Cs (with the over cab bed - pretty much like the drop down bed) but I don't know of any class Cs with 4 bunks either.
If you are in the market for used, the best option would probably be the older Newmar All Star 4156 which had an unfinished 'imagination room' at the back where you could easily put 2 sets of bunks.
Even custom built, if you are looking at new, the only ones I've seen with 4+ bunks are the 'entertainer' bus conversion which are probably more like $1+ million (sadly I do not think you would be able to get a custom built coach with 4 bunks for $250k unless you are updating a used coach).
Let us know if you find anything.