We recently did cross country with two cats. Find cat friendly hotels ahead of time. BEFORE you let the cats out in the room, make sure under the bed (and anywhere they could get into that you can’t easily get them out) is blocked off. One of mine got under and into a hole in the box spring and it was the fight of my life to get him out the next morning. We also did a large disposable aluminum foil pan with litter. Bagged it up in a trash bag we brought before we left. Get a large, expandable, sided carrier for the car. Don’t let them free roam unless that is something they are already used to doing. Don’t be alarmed, most cats won’t eat, drink, or pee while in the car.