Living in the Pacific NW, I’d highly recommended Rte. 101 along the Oregon coast (from about Cannon Beach south) down through Southern Oregon into Northern California. Beautiful scenic ride along the Pacific, many smaller towns in which to stop and grab a bite and relatively leisurely riding. I love it every time.
Also, riding into the Columbia Gorge on Rte 14 (the Washington State side) is terrific (the Oregon side, which is more picturesque, dis on I-84 which is too fast, too straight has way too many semis. But, you’ll see the best views from the Washington side, looking at Oregon). The Gorge is one of the most amazing places in the Northwest. You can stop at a number of small towns on the Washington side but, the gem is probably Hood River in Oregon which you can reach via a bridge and lots of signs as you get close. The further west you go, the less traffic and more desert feel it becomes. Go north to Walla Walla Washington the epicenter of some of the northwest wine country or south to Joseph, a beautiful little mountain town. Just about any direction you go, there’s great riding.
Having done a lot of riding down South, I’d also recommend the Blue Ridge Parkway and the Cherhola Skyway. These are some of the most scenic rides in the country. And you can almost smell the magnolias as you drive slowly through the small towns. It’s really a whole other world.