If you are starting or ending in Chicago, it looks like this one may not be a too far away, depending on your definition of "too far".
I don't know if this store is on Route 66, but the town is, and the place looks great!
Oops, forgot this one. I knew there was another I was thinking of. Had to hunt through a lot of bookmarks to find this one.
Not on Route 66 but if you are visiting Las Vegas there is the Pinball Hall of Fame Museum which is a lot of fun.