In eastern UP, there are 2 choices - US2 that hugs the Lake Michigan coast (and is scenic) and a state route across the middle, that is relatively straight, with forest and some rolling hills but not much else. There are a couple of side trips that you can take to the Lake Superior coast, as well as Taquamenon (sp?) Falls.
You could continue along the Lake Michigan shore to Green Bay, take a side trip up the scenic Door County, and/or head west across the state on a divided state route to I94. I94 takes you past/through the Twin Cities and on to ND and Montana.
Altnatively you could continue on 2 to Duluth. Possible side trips are the peninsula to Houghton and Copper Harbor. There's a state park and historic fort at the tip. And the Apostle Islands, with a scenic drive along the coast. In between are the Porcupine Mtns, one of the more rugged parts of the UP. And from Duluth, the drive NE along the North Shore is quite scenic, all the way to the border.
US2 west from Duluth is straight and flat (well a bit of a climb out of Duluth). It's a good alternative to I94 across ND and Mt. There used to be warnings about oil patch traffic and tight lodging in western ND, but with the drop in oil prices that activity has fallen off.
I'd suggest going one way along US2, and the other way across Canada, though there isn't a lot of difference in scenery in the prairie provinces/states. The southern Canadian cites are bigger than the northern American towns.
