Check out these northern routes.
Without time restraints and with no particular place in mind - my kinda trip.
Your reference to a northern route does not specify which one you are looking at. But if you get out your maps, you may like to check out the following:
Look at US12 and/or 200 across the northern route, especially through MT, ID and WA. These are scenic routes which at times will take your breath away. High speed limits, but on the whole lightly travelled, so ample time to mosey and stop to check out all the scenic and historic points of interest along the way.... more so on 12 than 200.
I could have taken a week, rather than a few days.
Then there is US-2, which is also a historic route and very scenic in places. Unfortunately completely clogged with oil tankers and traffic in the western half of ND.
Lifey