We don't really use price but rather ease and amenities for where we stop. Good place to let the dogs out is usually most important with the DW.
Tend to travel @ 62 MPH. This seems to be the most comfortable whether I had the jeep, the truck, or the trailer in tow.
Solo or with the jeep we get 12 mpg. Truck W/rzr or enclosed trailer we get 10 mpg. One of the benefits of having a lighter, bit underpowered diesel is the fuel mileage is good. The best fuel savings for us is just to get out of CA. Cross out of the state and fuel seems cheap.