We did the East to west coast trip two years ago with our three kids. Best trip we have ever had and hope to go again in a couple of summers. When planning the trip we, planned on 3-4 hours of travel a day and setup each night, so we traded our PUP for a bunkhouse to avoid the daily set-up, we also wanted to stay in Yellowstone, which does not allow PUPs due to bears. As others have mentioned, might want to consider a light TT. My $0.02 on the camper.
Otherwise plan ahead for any major attractions where you may need reservations, otherwise we enjoyed not having set locations, just ideas of where to go. We had reservations for Yellowstone and the Tetons, otherwise, we somewhat planned as we went.
Every night, we played cards with the kids, occasionally tried local cuisine, but mostly cooked for ourselves, made several stops at places just because they looked interesting. Take a different route each way to see as many things as possible.
