Sorry to hear about your friends' mom. I see you've gotten a lot of good advice for the Rockies. Got a good digital camera? You'll see scenery like never before. I have a cousin and his wife running team for ELITE CARRIERS out of Wausau, WI that have a weekly run to Vancouver, BC. If you're running the northern tip of Idaho, near the bottom of the grade on the east side of the state, there's an artisean spring with really good water if you carry water to make coffee. (I had a cheap, 12 volt coffee maker in the truck and that sure beat city water.) That would be easiest to get into when you're eastbound. At least there was a small pull-off when I was going through there.
Come to think of it, Lookout Pass where Idaho and Montana meet is high enough that you could hit some weather there now, already. I seem to remember that they do keep it pretty well salted when conditions warrant it. You shouldn't see any snow up there just yet, but frost is possible, and that can get a bit slick too if it settles on the road. Come to think of it, they use a "blend" of salt and cinders. I've gotten nics in my windshield from the cinders. But I envy you. I always enjoyed running up that way. Some of the most beautiful parts of the whole country, up that way... At least as far as I'm concerned.
Don't know what your starting point is, but looking at the truck stops at Monee, I'd be looking at 80 west to Council Bluffs, IA, then 29 north to Sioux Falls, SD. From there, 90 to Seatle. And, a good camera would be almost as essential as a GPS.
Good luck, Darlin', and enjoy the trip. Do yourself a favor and don't run off the road when "yer RUBBERNECKIN"...
If you would like a hint of what you're heading into.......
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