US97 in Oregon is mostly flat and straight, crossing pine forests at around 4-5000' altitude. The Cascades are visible to the west. In the north things are drier, and there's a drop to sealevel at the Columbia River.
In Washington it crosses three modest passes, and passes through a major agricultural area (orchards, etc). Part of the way is freeway (I82). After Wennatchee is stays at river level.
I84, US365, WA17 can be used to stay away from the passes.
In BC, the Okanogan valley is busier, with more orchards and vacation properties , and towns. 97C is an interstate quality connector to 5 (also divided), but it does climb on to a plateau area around Merritt.