We drove a Penske truck for 1700 miles, but we stopped BEFORE the Rockies.
It was by far the cheapest--cheaper than Pods, cheaper than UPack (a good option if you don't want to drive the truck, although parking the trailer can be an issue), MUCH cheaper than a van line.
Our costs were as expected--gas, meals, lodging. We did have a five-hour delay when the truck blew out a tire, but they refunded us $800 for our trouble. So for the four of us, that's like $40 per hour each. Not bad. It was a super-grueling trip--me in the car throwing Cheerios at the two toddlers wailing in the backseat, Mr. FP in the truck with the cat riding shotgun--but no regrets. We needed to save that money.
We did not sell all our stuff. We would not have been able to fit everything in our Accord anyway, and with four people, just our personal items (clothes, the children's toys, etc.) would have taken up a lot of space. And we bought a house 10 months later, so THAT'S when we unloaded the old dining room table and whatnot. We rented only a 16-foot truck, which is small for our number of people and square footage--we did pare down a lot of nonessentials (eg, our blanket trunk).
We did, however, have a CouchSurfing couple stay with us who had sold all their stuff and were moving in a station wagon. She was 8 months pregnant. They were from India, so presumably they had moved with a handful of suitcases once before!