Regards diesel or gas coach..... Gas
You will be unlikely to ever put enough miles on it to pay for the extra you paid up front for the diesel. And if things go wrong, more money.
The market is filled with 10-15 year old coaches with 40-60 thousand miles on them. People use them 20-30 days a year( in many cases) and they otherwise sit and take up space. And of course, they sit when you take them somewhere
I bought my 94 Tiffin Allegro Bay with 27,000 miles on it in 2005 ish. Had it 5 odd years before a divorce changed my situation and it needed to go
Payed 25k for it, everything worked, and did when it went by by. Nice coach
Can get a lot of bang for the buck in the 15-30 k range if you look, especially gas.
That all said.... i learned my lesson... a motor home, cost of buying it, maintaining it, once parked you need something else generally for store runs, out to dinner, etc.....plus storing the thing......... pays for a ton of 100 dollar a night hotel rooms.... a ton.
I like getting in my truck and getting out and about after racing and hanging out, heading to hotel, etc.