My friends all make fun of me for my "racer math", but given how we use our Class C it absolutely makes financial sense, staying in it about 40 nights a year at pro and club track events as much as 1000 miles from home. Any further than that, we do fly and hotel it. An example was our last big trip back in September-October. Left Thursday night from NJ headed to Auburn, AL where both kids are students. Wal-Mart'ed for a nap in Staunton, VA. Tailgated until Sunday at Auburn for the LSU game. Spent Sunday night at a Georgia State Park (FDR) near Pine Mountain, then drove up to Road Atlanta for Petit LeMans week on Monday where the big kid was driving in one of the support series. Stayed there through Sunday morning then home in one long drive that day. Cash out of pocket? 2000 miles of fuel at 8mpg was $575, the overnight in the State Park was $30, my competitor RV pass at the track was $200. We ate and drank well, so let's say $200 in groceries. Total? $1,005.
If I had driven my Golf Sportwagen, sure, gas would have been significantly cheaper, that 2000 miles/40 mpg = $112. But then, 10 nights in hotels, at at least $150 a night on average, because both these were high profile events, so $1500, then food at a minimum of $100 a day, so another $1000. Over $2,600.
Making this a fly-drive would have been even more. Plane tickets at even $250 each for my wife and I would have been $500. Rental car about $500. One night of hotel and a day of food saved would still be $2150. Way over $3,000.
We do trips like that 4-5 times a year. I've calculated that owning the RV over the 10-12 years I plan to keep this one (we're halfway through) will cost me in depreciation, insurance, maintenance and repairs about $5,000 annually. While all the travel and having the motorhome is discretionary spending, if we are going to do what we do, the RV easily "saves" the money spent on it.