If everything goes right I will be leaving the Seattle area the first week of October. Not exactly sure where I'll end up before I get to Quartzsite because it will depend on where a couple of my friends are at that time.
I take a longer inland route because the costs for gas, food, motels and repairs(should I need them) are less expensive than taking the I-5 or coastal route. My favorite repair shop is on the way in Cedar City, Utah in case I need it.
I take I90 east to I82 east and jump off at Rt 97 heading south(OR I stay on I82 and get off at Rt 22 south which runs into Rt 97, depends on my mood). I follow Rt 97 to Madras, OR where I jump on Rt 26 going east. This dumps me onto I84 in Ontario, OR almost on the Idaho border.
Now, in looking at the map this route looks insane when there is so much lovely interstate and scenic views to be had. I can answer that in one word: Cabbage.
Cabbage is a trucker nickname for Old Emigrant Hill in the Blue Mountains, a really gnarly chunk of I84 in Tutuilla, OR near the Umatilla Reservation. If you look at it from any mapping software it looks similar to a cabbage that's been cut open. Coming west on that road it's not bad but eastbound taxes the hell out of your vehicle both in steep uphills and hot brakes downhill. I've seen a lot of vehicle fires, overheating and break downs. My van is old. It's still alive. I'd like to keep it that way as long as possible.
Just to tell you how bad it can be, you can buy a tshirt saying you survived it at the rez gas station on the bottom of the north side of it. Now I'll only take the eastbound side if I am driving something I don't own, like a UHaul. No joke, the first and only time I took my current van up it someone with a newer pickup poured almost a gallon of water in at the truck stop in La Grande, OR. This isn't fearmongering, it's real.
Anyway, after I get on I84 I follow it through Idaho until I get to Tremonton, UT where I catch I15. I run I15 to Las Vegas where I grab I515 to Henderson, NV then grab I11. Now after this I have to make a choice; if I'm heading for Kingman or Flagstaff AZ I'll take Rt 93. If I'm heading for Ehrenberg, Quartzsite or considering stopping off if Jaimie's van build is going on I'll grab Rt 95. Once I'm on either I'm heading to my destination.
I go this route because the gas is cheaper on the way, if I break down I have access to a few more motels that will take a cat, repairs are cheaper, etc. That and I'm a creature of habit.