Late spring RT, Oregon - Iowa - Oregon

Having finally acquired my "always wanted one of those" car, now I'm planning my "always wanted to do that" trip.

Since my kids/grandkids live in Dubuque, I'm looking at an extended road trip -- up to 3 weeks, with enough layover time in Iowa for my children to get tired of Dad hanging around.

My first draft of a route:
Outbound..
Portland -- Boise -- Yellowstone -- Rapid City SD -- Sioux City IA -- Dubuque, with an extra day or so allotted for exploring Yellowstone and Spearfish Canyon/Deadwood/Badlands SD. Figure 7 days total.

Inbound..
Dubuque -- St Louis -- Lincoln, NE -- Cheyenne -- Vernal, UT (via US 40) - Wendover, UT -- Reno -- home, allowing time to drive as much of the old Lincoln Hwy (US 30) as possible. 8 or 9 days on the return.

Is this realistic? Ideally I'd like to take as many back roads as possible, with the knowledge this will cut down the mileage per day. But I'm not in a hurry.

Any can't-miss suggestions along that route, besides the obvious (Yellowstone)?

Welcome aboard the RoadTrip America Forums!

First off, you seem to have plenty of time for both transits, and you have shrewdly allotted more days to the longer return trip. Seven days is adequate for the outbound leg, keeping in mind that you could spend that long in Yellowstone alone. I made some suggestions earlier today for someone making basically the same trip in reverse, so have a look at those first and see if they're up your alley or if you'd like something else. As for the inbound leg, Remember that besides following the old Lincoln Highway, US-30 also travels in the ruts of the Oregon Trail. Unfortunately, the main display exhibit at Dinosaur National Monument is closed for repairs, but the drive south from Green River, WY through Flaming Gorge National Recreation Area on WY-530 was intriguing to me as a geologist, but do make time to do what I didn't - stop at the district office just south of Green Springs and get some info on what you'll be seeing

AZBuck