Hey friends, I just returned from 17,000 miles living on the road this summer. The greatest thrill of my life! I rotated between three or four different cars and people but most of the time I had a GPS and I would like to give some advice there. It was my first time in using a GPS and I will say that it is a nice thing to have in that it will tell you near by points of interest you might not find. However, beware to anyone making a cross country travel, if you are not having a 4 wheel drive it will often take you on little back roads. One memorable occasion was at 2 in the morning in the middle of nowhere Utah, the GPS trying to take me down literally an unused endless dirt road to get somewhere right off a main interstate, so unused in fact that there were weeds growing up so high it got all stuck up in the bottom of my car. This in a small car that does its best just to get moving. Because of that I ended up spending the night in a remote rest stop literally in the middle of nowhere. I always sleep in my car on road trips but in truck stops so this freaked me out!
Another would be in nowhere New Mexico trying to get to an alpaca farm in Mora again that is right off a highway... it decided to wind us up a one lane dirt road going up the side of a small mountain area... Lucky that my fiance is from India and used to such things so he had the idea to keep honking the horn constantly to alert anyone on the other side to avoid a collision lol.
The other occasions were going winding back roads all across Maine only to find myself at a closed road just a few miles from the destination, some times without a detour.
Anyway just a word of warning, GPS can be a great luxury, but always stick to your maps as back up as we should know. Most maps are clear enough to mark which routes are 2 lane highways, off road, etc, so check the direction the GPS is taking you in and make sure your car can handle it. Often there's a main route and it is only a few miles longer that direction.
HOWEVER.... one nice alternative the GPS does provide here is the back roads you will see are 90% of the time more scenic and of course so much more refreshing than main highways. My main word of warning is just about dirt roads for cars that can't handle them! Especially at night where there is no cell phone reception, not a good place to get your car stuck! :D