I did this back in 2002 when I moved from the Midwest to California.
I did it in 7 days which allowed me to spend a little bit of time at a bunch of places along the way, but it would have been much better to have longer. But then again, I tried to stay on the actual original road as much as possible which meant going 45mph on a frontage road right next to a major highway for much of Oklahoma and Missouri.
I used the Tom Snyder book also and would definitely recommend it as a resource. Some of it might be a little dated now (as far as structures or establishments that are still around), unless there's been a new edition.
I would also highly recommend making sure you head through Oatman (watch out for the wild burros while you are driving!). Arizona and New Mexico are great for natural attractions, and Illinois and Missouri are good for old-timey Route 66 diners/motels/gas stations, etc.