While you might have some time constraints, plan your trip so that there is something to see/do almost every day that is new or interesting for the kids. Sometimes this makes the trip a bit longer than planned, but it will be more interesting/enjoyable for the family.
Our family did not use "electronic baby sitters" on any of our trips across country. This is not a slam against anyone who does. We wanted our kids to "see" the country and talk about local history and geography. Our kids liked music, so we would try to play music that might be appropriate for a given area of the country. For example, we played the sound track from "Oklahoma" when we traveled through Oklahoma, and played the Beach Boys when in California, the "Music Man" when passing through Iowa.
Ask your children what they would like to see/do on the trip. You might be surprised. On one trip out west, our oldest daughter stated she would like to see the famous Spruce Goose aircraft in a museum in McMinnville (sp?) Oregon. She never expressed an interest in aircraft before, but wanted to see this one. So off we went to see the Spruce Goose.
You will create all kinds of memories, and it will make you feel good when several years later your kids say, "do you remember when we .....?"
Have a great trip.
