We reckon on 200 miles per traveling day at 7 mpg plus CG fees, mostly in the $30 to $50 a night. We don't tow a car, so we tend not to stay more than 2 nights anywhere. We do our sightseeing as we go. With current gas pries, and two nights every other place, that works out to around $125 a day, plus entry fees to tourist things if we visit.
As far as food is concerned, we eat on the road pretty much what we eat at home, so the difference is negligible (other than buying commercial bread instead of making our own).