The overall length differences are immaterial for going down the road and finding parking and buying gas and such. The wheelbase differences are unimportant for general maneuvering on the road, but they can affect the handling and general stability of the RV (longer wheelbase is nicer to drive down the road but does have a larger turning radius).
All other things being equal, I would prefer the longer wheelbase, even though it means a somewhat worse turning radius. It will generally make for better highway handling and weight distribution.
Typical Class C's are among the least maneuverable vehicles in parking lots and similar tight situations (including, perhaps ironically, some campgrounds). The turning radius of a stretched Ford E-series is not very good, and the long rear overhang makes for a good bit of tail swing. It's one of the compromises one has to evaluate. Still, there are not many situations where I've felt particularly hampered by the size of my (32' overall) class C. I would not care to drive through downtown Boston or Philly with it, granted; those are awfully good character building experiences even in a car. But most everywhere else the length isn't much if any trouble. (The width and height are more frequently concerning; particularly in construction zones, with Jersey barriers close in on both sides, it feels awfully wide!)