Nothing on 90 till you hit Mitchell, SD,
If you have the time, I would:
80 to kerney, ne, then north to chadron to rapid city through the really nice terrain to badlands, SD, mt rushmore > devils tower > Yellowstone, enter through east gate and make a look and exit through west gate and go north through earth quake lake and get on 90 > to 15 go up to 3 rivers and to glacier national park through the north gate and then come down south back through the park to 90,
MAKE SURE you go south through the park so you are on the inside lane, there are some NASTY drop you have to drive next to.
If you do decide to take I-70 instead of I-80, you will be very well rewarded. The drive from Denver towards Utah is gorgeous. It's a slower section of highway due to the mountain pass, but it's worth it. An extra benefit of I-70 will be Delicate Arch in Utah. Don't miss it. It needs to be on your A list.
I second what BHopkins said. More about the I-70 route:
Morrison, on the west side of Denver, has Dinosaur Ridge (a short walk to a hillside full of dino tracks) and Red Rocks Amphitheater and Park (amphitheater and some short trails with great views of the foothills and Denver skyline. They may also be drag racing at Bandimere Speedway, between the two. You might not be able to visit Red Rocks if a concert is scheduled that evening.
Farther west of Denver, you can exit at Idaho Springs and drive to the top of Mt. Evans, el. 14,264.
Almost any rest area between Denver and Glenwood Springs will have scenic views.
Colorado National Monument is just off the interstate at Grand Junction. I've never been there, but hear it's similar to the Moab area on a smaller scale.
You must drive Highway 128 from Cisco to Moab if you're in the area. Delicate Arch is something like a 3-mile roundtrip hike once you get into Arches National Park. You may as well spend the day there if you go. The Devil's Garden hike will let you see 4 or 5 arches in a couple hours of hiking.
I just checked out Sego Canyon Petroglyphs on Tripadvisor--they look easily accessible from 70 between Moab and Green River.
You'll probably cut northwest from Green River to Salt Lake. If you like birds, visit Bear River Migratory Bird Refuge on the Great Salt Lake, north of SLC and Ogden. The Golden Spike Historic Site, where the transcontinental railroads met, is out that way in the middle of nowhere. I've always wondered what it's like.
That's where my ideas end. I haven't spent any time west of Yellowstone.
What is your specific timeframe, and how far are you willing to hike to see something?
Are you planning a straight A to B trip, or would you want to meander some on the back roads?
It's a road trip as much as it is a move. I'm going to spend a few days planning it from POI to POI after I compile a list of things I want to see. It just needs to generally head in that direction with basically no backtracking or going 300 miles out of my way just to see a big rock or something. Of course there's a few routes I can take in general from point to point. I'd be willing to drive maybe up to an hour out of the way for something great.
From the looks of it, 4 or 5 days would be the max I'd want to spend from Kentucky to Oregon. 800 miles can be done in a day if need be, but out of the ~2500 miles, it'd be easier to split it up into say 600ish miles a day average, and spend 5 days tripping.
It sounds like you'll be limited to true "roadside" attractions and things located on loop roads off the interstates.
It it was me, I would drive hard for the first two days. That should get you to the Badlands or the front range of the Rockies by the second evening. Once you get into mountains, a lot of driving you do off the interstate will be slower than you expect. Most national parks also have a 45 mph speed limit. Making time at the beginning will allow more time for sightseeing during the last few days.
I just found out there's a national monument about the MX Missile, right outside Badlands N.P.