You make some good tradeoff points regarding the SS models versus our Itasca. Yeah, you're right - Winne no longer offers our floorplan on the Ford or Chevy.
What I've thought about doing is swiveling our passenger seat and keeping the lounge chair so that folks could sit in the lounge chair, swiveled seat, and whole dinette to visit ... or sit in the lounge chair, swiveled seat, and right half of the dinette to watch a TV swung out from the wall behind the left half of the dinette. However, ours is a "basement design", which makes the coach floor about 4 inches higher than the cab floor - so I'd prefer a passenger seat swivel mechanism that both swiveled and raised a bit.
FWIW and for reference: Ours came with such things as 12 volt electrically heated (for heating w/o the furnace on) tanks, water filter, outside entertainment system, outside shower, electric steps to keep the door sill high for good ground clearance while still keeping the step-up low, fiberglass single piece crowned roof with full rolled sides, molded fiberglass roof end gable caps, enclosed steel lined tank valve and electrical service cabinets tucked up high for good ground clearance, steel lined wheel wells in case of tire blowouts, double galley sinks, all aluminum internal wall framing, remotely controlled dash radio, electrically heated and driven side mirrors, full height shower stall for tall folks, two steel lined cross-body exterior storage areas for long items in addition to four other steel lined exterior storage areas - one of them being large, spare tire mounted out of sight up high between the frame instead of on the coach rear wall, battery storage area large enough for two Group 31 batteries, battery compartment accessible from inside the coach, easy access cab overhead bed because of the raised coach floor, dash radio speakers throughout the coach and cab, several 12 volt receptacles including a heavy-current one for laptops, several 120 volt outlets, alternator charging of all batteries, 18 gallon (61 pounds usable) propane tank, the optional E450 chassis, and a coach floor with carpeting on the dinette floor, carpeting around the lounge chair, simulated tile vinyl in the galley and bathroom areas, multi-ducted heating, multi-ducted air conditioning, steel drawer slides with gravity locking, solid hardwood cabinetry fronts, boost switching of coach batteries for enhanced engine cold weather starting, chrome wheel liners, engine or coach battery source switching for the cab radio, weather band cab radio, auxillary input capability for the cab radio, swing-out galley counter top extension, dinette conversion to a full size bed, and aluminum cab steps instead of fiberglass.
I apologize for the long description ... but I just wanted to be thorough to help with things to look for when shopping.
P.S. You might be right on the Chevy 4500 riding rough like our E450 does. However, in my communication with the Koni shock company, they stated that their Frequency Sensitive Damping (FSD) shocks are expected to be available in January for the Ford E450 chassis. Perhaps they'll have a part number for the Chevy 4500 chassis soon, too.
Good luck, and keep us posted.