US97 is relatively flat and straight from Ca through OR, about 4000 ft, through Ponderosa Pine forest, with Cascades to the west. The 138 climb to the north side of Crater Lake is the highest pass to the west. Oregon 'out-back' is to the east, with some interesting volcanic and high desert features (especially around Bend).
North of Madras it drops to the Columbia River. 197 is an alternative with the same drop.
In WA 97 climbs over a modest Satus Pass to I82, and another pass (high speed traffic) to I90. There's a more relaxed winding road along the Yakima River canyon.
And a bit bigger pass to US2 (Blewett). These passes all have WSDOT pages and webcams.
I haven't driven 395 in California. Last time I took FS roads across the volcanic highlands into Or. Lake City is supposed to be the highest incorporated town in Oregon. As far as Burns 395 is in the northern extension of the Nevada basin-n-range. Then some modest mountain passes to the Columbia.
In WA 395 is freeway NE to I90 and Spokane. I believe WA17 is the best way north and northwest. North of I90, you can drive from Quincy to Wennatchee, with a modest drop to the Columbia.
