We upgraded to Class C 4 years ago for same reason: We were planning some longer trips-- It is amazing how convenient it is; so much less stopping. One trip from Maine to Florida, I drove thru the night to get south of DC before dawn. The kids slept on the couch and the dinette. I stopped for a 2 hour power nap in my bed. Everyone was rested to continue all the way to SC! Could never have gotten that far in the Durango w/ TT. Kids enjoyed the ride-- watched DVD and played the X-Box on the couch. Fuel economy is not much less-- we are able to save w/ the daily driver by not needing a gas guzzler V8 Hemi to tow a TT handful of times/ year. We average 1 week and handful of long weekends.
My 12 year old (who has Aspergers- LOVES the bunk over the cab).
I have also found alot of camp grounds have shuttle buses so not having a vehicle had not been much of issue. We had planned on buying a tow dolly but keep putting it off.
Best move we ever made was the Class C!
Good luck with your searches!