Vancouver Island to Glacier National Park

Thanks for the info, just what we wanted to hear. It all looks good.

X2 what Paulj said

Someone else was just asking about 20 across the whole state. The part west of 97 is the most scenic, but your BC3 is good in that regard as well.

East of 97 is the same sort of mountains and river valleys as BC3. There's a pass east of Republic, highest paved one in the state, but few people talk about its grades.

An alternative is a diagonal from 97 to 2 via Grand Coulee dam. While it climbs a bit, the main grade will be on the climb out of the dam gorge. That's through a town.

If you consider BC3 to be suitable for your RV, then WA20 is aswell.