If you are into Geocaching and are a Premium member of the site, you can plan caches along a route. Below you will find a publicly shared folder with the GPX files I used when planning our trip in 2018. When multiple alignments of Route 66 exist, these files attempt to follow the oldest, although that is not always the case. These make a great starting point but you will want to tweak them depending on your preferences.
GPX files are useful for many mapping applications so even if you have no idea what Geocaching is, you may find these files useful for planning your Route 66 trip.
In addition to the GPX files, here is a link to the spreadsheet I used when determining our stops for along the way: Route 66 Spreadsheet
Here are the links to my “Route 66 Retrospective” blog posts where I discuss our planning process and how the trip came together as well as lessons we learned on the Mother Road.
And, of course, this page would not be complete if I didn’t include a link to our YouTube series from our trip: