a phone is a pretty small screen to see the big picture what planning your route...
Ive tried it, but its just not as functional as a real map.
we always prefer to travel the scenic routes unless there is some hurry to get somewhere, which isnt often when we are on a roadtrip..... and I use the Gazetteer maps that are found in nearly any sporting goods store you go into... there is the red cover version, and the black cover version, I prefer the black cover gazetteer, but I always buy both when I can, as each has its pros and cons, and with both you can get a pretty accurate mental picture of the route...
they are of a very easily readable scale/size, so nearly all interesting features of the area are listed on the map...
