We're currently DP owners and the question you raise about additional seating is a good one. The current rig we've got has facing sofa's on both sides of the motorhome. Viewing is through the side windows and front windshield.

From time to time, as we talk truck conversions, I ask my kids whether they would like sitting in the box of the conversion and not being able to see out the front windshield. The answer from them is usually "who cares" as long as we can see the TV. I've been able to sit in Bill's rig a couple times, and there are advantages to having the isolation of the driver in front...kids in back.

I think I'd stick with the side facing seating to avoid loosing space, and possibly use larger windows in the sides of the conversion to "open up" the space.