Regarding my recommendation to get a Tom Tom (or other satnav for that matter)
Now this I have disagree with, when I have been we never total plan our trip. We find it much better to be free to go off route and explore, I know of many people who have done the same USA road trips as I, but missed stuff because they had to get to the next booked hotel.
I think you may be making wrong assumptions on how I (or others) use satnav. Having to get to a pre-booked hotel isn't the same thing as using a satnav to get around.
I too drive freely with little forward planning, making it up as I go along. Trips of up to 7000 miles in a month. This doesn't stop me from using satnav to help out here and there, especially where many US roads are poorly signed, or appear without no prior warning and then with a tiny easily missed sign. There is no way I plan a whole or even half day's driving A to B using satnav. I might put in a destination some distance away just to get me on the right road and give me an approximate distance and time to.
I still use plenty of maps, and I use a compass a lot. Getting around US cities and towns is easily accomplished just by using a compass to head say west to get to a freeway entrance or get out of town. And of course, satnav units have compass directions.
I don't make many hotel/motel bookings in advance. It depends on destination and likely availability. Obviously you have to have the first night booked somewhere for US immigration address purposes, but most of the time I stop wherever I get to by the evening and find whatever's available. It's very liberating, as I'm sure you know.
It has got me in to and out of places where a map failed, or was just too difficult to use, like driving alone round the San Francisco streets without having to find places to stop (almost impossible) and keep looking at a map. Like trying to find your way out of the airport and get to your hotel. And if you remember to locate the car rental place on the satnav before leaving, it can get you back to it on return, which in itself can be a difficult and very stressfull task despite their instructions and map.
A satnav doesn't stop you exploring or driving freely. So long as you don't become a slave to it and use it with common sense it's an excellent and useful tool. I lent mine to a friend last year for a 2 week road trip and he thought it was amazing. The Tom Tom is still a damned useful thing to have and I wouldn't be without it.