Two years ago, I moved from the Philly area back to California. I got rid of a lot of stuff, but also shipped a lot of things or took them on the plane with me. Too much stuff.
Now Nathaniel and I are headed back east, making a similar trip, but with two people. Nathaniel's belongings have always been sparse, but I know I need to pare down again, which I look forward to doing.
Originally I thought we would rent a truck and tow the car, then I thought we would drive the car and tow a trailer, and then I decided that the cheapest option would be to drive the car and ship some things (books, bulky blankets, etc.). Media mail is cheap, so books weren't a problem, but I also discovered Amtrack Express Shipping for the other stuff.
The way Amtrack Express Shipping works is you give them a whole bunch of boxes as a "shipment", total weight being a max of 500lbs. Each box can't be bigger than 3'x3'x3' or weigh more than 50 lbs. Then, they weigh it all together and from Emeryville/Oakland drop off to Newark/Philadelphia pickup, it's $67 for the first 100 lbs, 57 cents/lb thereafter. For reference, USPS Media Mail over the same distance is about 50cents/lb, for a 20-50 lb box, but you can't pack your media items with soft-but-useful things like clothes, for instance. All other kinds of shipping are well over a dollar a pound.
I think we'll ship books, Ruddy the Big Red Blanket, winter clothes, and other bulky things this way. Then we can pack up the car with some small furniture, my guitar, and the bikes (there's a bike rack), along with other small stuff like the clothes we'll need for the trip, artwork, and maybe the two small plants that I'm fond of. If we end up using the whole 500 lbs for shipping, that's only $300, less than the cost to get a hitch for the car, let alone to rent a trailer, plus it won't decrease our gas mileage as much.