Just between Chicago and St. Louis alone there must be a 100 plus places outside of the normal ones worth seeing, either on, or close to the route. So in a way when you visit the route you can see not only the normal landmarks but a bit more depending on your interest.
Route 66 has points of interest for agri-tourism, culinary tourism, paranormal tourism, American history, automotive history, aviation history, railway history, sport tourism, American Kitsch, and spa's. The list goes on, yet also the list tends to stay family friendly.
Bachelors Grove Cemetery is a renowned ghost hunting sight near 66, one of many on the route
St. James Winery a Route 66 must stop for wine lovers.
Agri-tourism? Funks Grove is an excellent example.