If you are going full size, definitely go 3/4 ton. And unless you find a great deal, if you are not towing get the gas engine.
My experience with fuel economy, once loaded up on the highway a 3/4 ton will get as good mileage as any other smaller SUV or pickup. Sure they get better mileage empty, but throw on an RTT, a lift and bigger tires and they all get horrendous gas mileage. A least with a 3/4 ton .... as long as it is not the PowerWagon .... you will not need to worry about over loading it. And keeping it running... if you stay stock... maintenance and tire costs are the same too. Actually 235/85R16 tires are one of the best buys out there and you will get better gas mileage than a lifted Tacoma on 33s.
If economy is important, stick with stock tires. Stick with the base payload package, the heavier packages include lower gearing and are tuned to haul. It sounds like the base 3/4 ton will do it all for you. On tires, I just went from the typical Wrangler on 33s, best of 17mpg, to 7.50R16 pizza cutters, skinny and light but still tall, I now get 22mpg. An instant 95 mile addition to range between gas stops.
Find the best deal on a gas 3/4 ton with a clutch and expect years of trouble free service. As for ride, I prefer the solid feel of a 3/4 ton over the wallowing feel of a 1/2 ton. If it is a Ford it'll ride great. If it is a Dodge.... at least the previous generation... it'll ride like a buckboard.
3/4 tons ride best loaded. 1/2 tons ride best empty.