Don't leave home without them.
Like Donna, I too travel with a box full of maps. After crossing a State line, I fold up the map of the State just left, and get out the map of the State entered. You really can't beat good maps. Computers will not give you that big picture.
As you read through these responses, you will see that we are united, you cannot get a sense of the routes available to you, without good paper maps. Besides routes, you will also see on most maps where the scenic routes are, should you wish to leave the interstates for a break. Many attractions, historical, geological and touristy, will be on those maps, and who knows what else you may find that interests you.
You really can't leave home without them.
Lifey