We just drove from Boise to Lincoln City (with a stops at Walla Walla, Columbia River Gorge and Portland). We used I84 instead of Hwy 20.
Once in the Portland area, I'd suggest avoiding 26 from Portland to the coast and going North through Astoria to the PCH instead. 26 isn't all that bad but other drivers are on your tail hoping you'll pull over, and that's while doing the speed limit plus a few miles over. There weren't many spot to pull over, and only 4-5 passing segments. To me it was a very aggressive road experience.
We pull a 34' FW with a F350.
No longer full timing, but still camping 10 days at a time every other month.