A couple of variations. How much time are you allowing for your trip.
If you are using 97 to Bend, Cascade Lakes route parrallels 97 between Crater Lake and Bend.
395 is a good straight thru route from CA to Spokane. Lots of variety. Big two lane.
Bearing east from Bend you could explore the Fossil Bed area. Shaniko, Mitchel, Spray, etc. Nice riding and a fossil museum on 207 (I think) I use 207 to get to Hermiston. Very scenic. Desert cattle lands.
From Hermiston you can follow the south side of the Columbia to Hwy 12. 12 is a good scenic road from Montana to I-5. Very nice road.
Left at 12 will take you to Pasco. Sort of a Mexican town in WA. At the Lewis Street exit (off 12) Left into town for truck taco stands or turn rt/north toward Kahlotus. This is a rural paved farm road along a ridge top thru farm lands. It is better going south, but still a fav of mine. At Kahlotus turn rt toward Washtucna. You can visit Palouse Falls along this route. Just a few miles to the south. At Washtucna you will tee at a hwy 26 ( a major two lane), don't turn, go straight across onto the tiny paved road. It looks like a driveway service road. This will take you straight north to Ritzvill on I-90. Zoom right into Spokane.
You can access Palouse Falls from hwy 12 also. At Starbuck. Tiny town with really big fishing shop.
there are a couple places to bear north off 12. You will probably end up on 195 ties into I-90 at Spokane.
If you don't have business there try to skirt Spokane. The largest population area in the inner NorthWest. Spokane - CdA- Sandpoint is dense with people. South and west ot Spokane or east of CdA the population thins dramatically, more people to the north of I-90 thru here and no fast roads going north. Traffic lights galore.
I use hwy 20 - 31 north of spokane to go to Canada. rural and tiny border station. After crossing into Canada the road tees. Rt to Creston, left to Sumas and Nelson. Nelson is a fun town to visit. Lots of walk around shopping, ice cream parlors, tea shops, etc. North of Creston is one of BC's best bike roads. north to the free ferry and cross to Nelson to north ot Kaslo and around the Selkirk Loop (google it) You can get north to Banff from here via rural pavement. Gorgeous area, nice roads.
+1 on route 40 in Alberta and north out of Banff and Many Glaciers in MT. Babb, MT has a big steak house.
this would be a good route south then make a route thru MT or ID.
Hwy 93 from the south Bitteroot valley to Craters of the Moon is very scenic. Love Dillon MT, big sky country.
:You could work in the Great Basin area on the way to SF. South from Mt Home ID to Eureka NV and west on hwy 50 is a very good route out of ID.
Dillon south on I-15 into ID. East toward the Wy border thru Driggs, Tetonia, Swan Valley, Snowville to Wendover the the Salt Flats. West on 50
And on and on. Anyway that is a few ideas to roll around.