Funny, I live in MN, but used to live in Oregon, and have a couple friends (and spent some time) in Corvallis. What a fun place ... mmm... American Dreams Pizza ...
Anyway, the route to take depends on what you're looking for. Scenery or curves? If you have a passenger, I would guess Scenery, and will base my suggestions on that. And no reason to choose between Beartooth Pass and Glacier. Do both!
I blog about my trips - here is the start of a trip from MN to OR and CA. From this page, work your way to the present. I have some photos and trip descriptions of the areas you're riding through .. think I've bene through it a couple times in the past couple years:
https://norskiesblog.blogspot.com/2009/08/belvidere-south-dakota.html
If you haven't already done so, take 20 east to 126 to 242 to Sisters. This will take you through the lava fields and the Belknap crater, then lunch in Sisters.
Then go east again to 97 to then 26 west to Mt Hood and spend the night at the historic Timberline Lodge (if you don't mind 20 miles of gravel, there is a "shortcut" from Sister's to Lake Billy Chinook and The Cove Palisades).
If you (and your wife) haven't ridden through the Gorge, I would put that at the top of the list, and from Timberline Lodge to west (towards Portland). In Sandy find Ten Eyck Road and other shortcuts through Bull River Run to the Columbia River Highway. If the weather is nice then a trip up to the Larch Mtn viewpoint is totally worth it - you won't get a better view of Mt Hood (except maybe from a plane).
Back into the gorge, and hit the interstate east. This is the deepest and most scenic part of the gorge - if you only see it from Hood River and east, you missed the best part. If you have time and want a slower pace with stops at lots of waters, take HWY 30. BTW the Iron Horse brewpub in Hood River is fantastic! Too bad beer has alcohol, and this brewpub tends to have 7-8% brews. Great if you've stopped for the night .. if not .. sorry to tempt you. Yeah ok Full Sail is in HR too.
At the Dalles, get gas and cross over to Washington and take SR14 east. Stop at Stonehenge. Not much gas from here until Umatilla, so that's why you had to get it in the Dalles. Go back to Oregon in Umatilla.
Now you've got a choice. 730 to hwy 12 over Lolo to Missoula, or the much longer route south on 37 to 204 to 82 to Enterprise and through Hells Canyon (don't forget to take the little road up to the damn from Oxbow). Then 71/95/13 to Kooskia, ID where you pick up 12 and go over Lolo.
Lolo Pass is a beautiful road, but due to the traffic and enforcement it's not a pegscraper. It is engineered well enough to do so, but you'll have to exceed 100 mph to do it, and it just ain't worth it (to me). Mellow down and enjoy it - and yes, there are easy places to pass. Once over the pass into Montana the speed limit picks up and the road down to Lolo, MT is an absolute blast. Speed limit is 70 mph, so you can get some fun without overstepping the law too egregiously.
Alrighty, you're in Lolo, now what? You're still far from Yellowstone and Glacier. I've done both many times and feel Glacier is the winner. Yellowstone is for RV's and going slow and taking your time and see all the little details and paint pots and stuff - other than the canyon and the eastern entrances, there's not much scenery, so my nod goes to Glacier (but that doesn't mean you can't throw in Beartooth pass!)
From Missoula to Glacier go around Flathead Lake (I prefer the western side - less development, more lake views). If you want a sidetrip, the Koocanusa dam and reservoir to the northwest is a joy to ride along, but is out of the way.
Anyway, there are three ways to enjoy Glacier: Once through (4-6 hours), twice (a full day) or hiking (2+ days). No matter how to get through Going To The Sun Highway, do it with the sun at your back so the mountains stand out in awesome detail. From the western entrance to the start of the switchbacks is sort of boring, but then you rise in elevation and it's bliss from there. If you can only make one pass, try to go from west to east in the afternoon (i.e. sun at your back).
If you can, ride Hwy 2 along the southern edge the afternoon before and position yourself near St Mary so you can start from there in the morning (breakfast at the Park Cafe is NOT to be missed!). Then spend the morning going west, turn around before you get down to lower elevations again, and then go east in the afternoon. There is a shuttle system in the park which is nice if you're camping and hiking so you don't have to get back on the bike for a day or two, but you'll get better views of the mountains without a roof over your head (just be aware that traffic can really slow things down).
If you have time to hike you'll see the best of Glacier ... but that's a different post.
Alrighty, after Glacier, leave the eastern edge and avoid taking the High Line to MN. There's nothing there to see.
Instead, go south through Great Falls, Hwy 89 to Wilsall then 86 past Bridger Bowl to Bozeman. Stop at the Pickle Barrel, the Campus Location. This is a Montana Tradition, don't miss it, and buy an extra sandwich to share later down the road. And there's Wilcoxson's ice cream in home-made waffle cones next door. BTW if you go through Helena and end up in Three Forks, check out the Lewis and Clark caverns.
From Bozeman go east on I-90 (not many alternatives, but this isn't a bad section) to Columbus, then Hwy 78 to Red Lodge. That's the gateway to Beartooth Highway, which connects up with Cheif Joseph Hwy to Cody. Prepare for cool temps, hail, snow, tourists, and frequent stops to absorb the views. In my opinion, this has got to be the most scenic road in the US.
From Cody you'll have to cross the Bighorns. If the weather is bad, take the south route, 16, as it is a lower, straighter road. Don't forget to check your mirrors to see the Grand Tetons on a clear day.
I prefer the northern route of 14 because stays in higher elevations longer, but the southern 14 is nice too as it winds up through a tight canyon. Beware these mountains - we've been snowed on in June, July and August, experienced thunderstorms, and at dusk the antelopes come out.
After the Bighorns consider taking 14 through Clearmont to get across Wyoming, instead of I90. It is much more scenic and interesting.
Devil's Tower is a good stop too, and then Spearfish Canyon in the Black Hills. If you can find Nemo Road, that's a good option.
From Rapid City I've always enjoyed 44 to 240 through the Badlands. Resists Wall - it's a tourist trap.
After Cactus Flats depression will start to set in. Stop in Murdo at the car museum for a break (they have some bikes too).
In Chamberlain you'll be amazed at the topography as you cross the Missouri and stop in at the rest area to learn about Lewis and Clark. While you're standing up on that overlook over the Missouri, you'll realize that what you what was amazing topography here is really nothing, you were only impressed compared to sitting on I-90 for hours and hours looking at a straight line, sweating, fighting the wind, etc. You realize that the Bighorns was the last place you were truly happy. As you think about the rest of the road going east, you think to yourself ... "Self, can I just stop here, and go west again?" but no, obligations force you eastwards to the vertically challenged upper midwest. It's all you can do to get back on the bike. As you cross into MN and pass Luverne, Worthington, etc the hours of riding on expansion joints jolt you back to the land of frost heaves. While you plan your next trip west, you can console yourself with frequent trips to the beer store, alphabet roads, spend the winters farkling and reading this forum.
