+1 on Smitty’s suggestion. I live just north of Des Plaines and that is how I would go to avoid as much traffic as possible.

 

Ok i don't want to change your mind on Milwaukee, but if you have already been to the museum, why are you doing the pilgrimage again... traffic around Chicago sux, what day of the week are you doing this, it does matter....
if I was you i would one of these two routes...
1) head northwest to Lake Geneva, beutiful lake on the Wisconsin border.....I90 west to route 47 straight north....in woodstock stip at the worlds larges HD dealer it is in an Super K building....then downtown Woodstock where groundhog movie was filmed in its entirety...the to Lake Geneva, take a boat ride around lake then take route 45 south to o'Hare.
2) take I90 west to Rockford stop at the Kegel HD dealer, it has an old train diner attach to it, it was featured on the top 10 stops for HD riders, also the olders HD dealer in the world.
The follow Roite 20 west get off at route 2... take eoute 2 south it follows the Rock River, great ride...to Dixon Illinois, visit President Reagan childhood home, nice little guided tour, the start heading back to O'Hare via route 64....

Just an idea.......

 

I'd add in time to tour the Pilgrim Road Engine Plant.

 

This does sound like a solid trip for sightseeing. The only issue I have is all the I90 riding, I prefer to try to get on some backroads whenever possible.

I'm ok with skipping a few of the sightseeing things for a better ride.

I'll play around with the map and see what I come up with.