Been on about all of those. A few to add:
Spiral Highway, old Lewiston Grade, Lewiston, ID
Hood Canal - Hwy 101 from Shelton, Wa to Quilcene, Wa
Hell's Canyon - Baker City,Oregon to Cambridge, ID
Rattlesnake Grade - Clarkston, WA to Enterprise, OR
Dooley Mtn SW of Baker City Oregon
Hwy 395, Pendleton, OR to Burns, OR
Northern Calif - Hwy 36 and 96 (Klamath River Road)
Hwy 25 on east side of Lake Roosevelt.
Washington Hwy 261 thru Starbuck.
Have to agree with Motion about Beartooth.
The Teton's near Jackson Hole, WY
About anywhere in Western Colo
(Skip Mt Rainier - cobby pavement and packed with tourists)