I've read quite a few posts indicating that the ride quality tends to be better with 22' tires.
Based upon a brief search, I think the 2012 Vista has the Schwintek slide out mechanism on the larger slide. That would make me very nervous as there were many problems with the system when used with larger slide outs. We had a Winnebago travel trailer with a Schwintek slide out mechanism on a smaller slide out. I never had any problems with it, but from what I've read, I would avoid them on larger or full wall slide outs.
I would also suggest looking at other brands, in particular Tiffin or Newmar. During our search for a used gas motorhome, we looked at quite a few units and found that Newmar, Tiffin and Winnebago were our preferred manufacturers. We're very happy with our Newmar Bay Star and find the quality to really be top drawer, especially the insulation of the unit. Newmar actually provides the R ratings for the roof, walls and roof whereas I could not find that information for the Winnebago Vista. But, I will say that the wood cabinetry of the Tiffin gas motorhomes is better than Nemar's.
2012 Newmar Bay Star 3302
Blue Ox Avail
BrakeBuddy Advantage
2015 Malibu
"Get busy living, or get busy dying."
Andy Dufresne, The Shawshank Redemption