Also,what are good places to visit?
If you have an idea of what state or area you'll be going through, I can make recommendations. Otherwise, I can offer the generic comment that National Parks are usually worth the stop.
Some other travel tips:
Buffet-style restaurants are usually a good deal in terms of food. If you're in the Western part of the US, look for Golden Corral restaurants. Ryans is another good chain. You pay a flat fee and it's all you can eat.
You can often get good deals in truck stops. (Yes, really.)
If you can get breakfast with your room, make that a major meal for the day. If possible, plan for a late lunch (between 3 and 4 p.m.). Many restaurants will have cheaper prices during their lunch times, sometimes for the same meal you'd pay more for at dinner. Lunch prices generally end around 3:30 or 4 in the afternoon.
Bring your own packets of microwave popcorn, your own cans of soda if possible, and so on. This is cheaper than buying things out of a vending machine. So is shopping at the local supermarket, as opposed to the local convenience store. Many hotels now have microwave ovens in the rooms, or at least in the lobby, so you can heat some of your own stuff. Don't buy bottled water; do carry a water bottle, and use the hotel's ice cubes and water to fill it in the morning before you head out.
Check the hotel lobby for coffee pots, or containers of hot water that will let you make your own hot tea or cocoa. A lot of places have that for guests now. Plenty of places also have swimming pools, many indoors, so take a swim suit.
This may just be unique to my family, but we try to have some empty space in our suitcases when we start out. That way, we have room for souvenirs and other things we've bought on the road. If worst comes to worst, you can always mail things home. I often use vacations as a way to pick up Christmas or birthday gifts for people, especially things that we normally couldn't get at home.
If the hotel doesn't have do-it-yourself laundry facilities, ask for directions to a local laundromat. My parents usually carry a plastic container of detergent so we don't have to buy any, but that's up to you. I don't think it's that expensive to buy detergent in the laundromat, and you don't have to cart it around through your whole trip.
Clean out the car and organize stuff in your suitcases every few days.
