Ahhh, yes, the dilemma us family folks with children must deal with - Wanting the children (and adults) to have their own private space in the RV, yet still want the luxury and convenience a Motorhome brings. This was one of the reasons we stuck with an RV trailer (with quad bunkhhouse in back) for many, years, and hesitated to go to a Motorhome.
Where to put the bunks where the kids can have their own space, without intruding on the privacy the adults need/want, in their bedroom in the back. :)
I've looked at models like being discussed here, where a closet in back bedroom is converted to bunks. Absolutely HATE that arrangement and want nothing to do with it. We need a bit more privacy than that. Don't want kids to have to come tromping through our bedroom at night when/if they need to use the bathroom, haha!
Also seen a few where a large wardrobe/closet in the hallway is made into bunks. Basically, the bunks in that case are an 'afterthought'. No windows in the bunks, and no TV/DVD in them. Didn't like that, either, would like to give the kids a nicer space than a converted closet.
The ultimate bunk floorplan I've seen, was one floorplan Gulfstream RV briefly built a few years ago, that had the bunks in a completely separate room, forward of the bathroom. Completely separate room (with its own door), with bathrrom between it and the back bedroom. Only saw one of them on RVtrader, and it went away quickly.
Ultimately, we settled on the Georgetown 351DS model, with has the very common floorplan with bunks just outside the bedroom across from the bathroom. To address the privacy issue, first thing I did was install a 'hook and eye' type lock on the bedroom door, so we could lock the door when privacy was/is needed. Have been camping with it now for almost 2 years, and its been great.
If you really, really need ultimate privacy between the kids bunks and your bedroom, a towable RV makes more sense. Just can't beat the privacy of having the kid's bunks on one end of the rig, and your bedroom on the opposite end like many towable RVs offer. Thats what we had for years, and sometimes I miss that.