I've driven parts of Route 66. From Joliet IL to Springfield IL and from Williams AZ (just south of the Grand Canyon) to Needles CA.
You will find interesting buildings along every part of Route 66 to stop at, so expect lots of stops everywhere you go.
Odell IL - restored Standard Oil Gas Station from the 1930s.
Pontiac IL - Pontiac-Oakland Museum, and Route 66 Shield Mural (take a picture of car in front of it) - in the alley behind Route 66 Association Hall of Fame Museum. Also check out the murals across the street / in the alley with the Route 66 Shield Mural. They're pretty cool too.
You will also find small gas stations and restaurants, old buildings along the way. I recommend getting off I-55 and onto Historic Route 66 just south of Joilet and driving Historical Route 66 all the way to least Pontiac.
Seligman - Historic Route 66 General Store - basically a souvenir stand but its still cool. There are other gift shops in town worth checking out.
Hackberry - Hackberry General Store. A red Corvette, old gas pumps, signs, etc. Lots of old cars to look at out back too. Nice souvenir shop. This is a must stop for any car guy.
Kingman - mention in the song "Get Your Kicks on Route 66".
- Locomotive Park - steam powered trains and train memorabilia
- Route 66 Museum - across the street for Locomotive Park
Cool Springs AZ
- Cool Springs Station - looks like something out of the "Cars" movies
Careful driving and some slow speeds from Cool Springs into Oatman - this is a mountain pass and the road is narrow in places. You might even see a wrecked and rotting car corpses in one of the ravines.
- Careful driving though Oatman - there are wild burros running around. These burros are descendants from the burros that gold miners set free after the mines closed.
- Feed the burros - While the burros are wild, they have little fear of man since the townsfolk and tourists alike feed them. Several places sell burro feed and they should come up to you if they see you have it.
- Check out the old western wear and memorabilia in the various tourist shops in town.
Now I haven't been to Amarillo Texas yet but
- Cadillac Ranch
- Route 66-Sixth Street Historic District
Oklahoma Route 66
- Lucille's Gas Station - Hydro, OK
- POPS - Acadia, OK
- Famous "Blue Whale" - Catoosa OK
- Will Rogers Museum - Claremore OK
- Optimus Prime (Transformers) statue - Stillwater OK
- Oklahoma City - Check out the state capital complex - complete with working oil rigs on the property!