I-40 across the country

That's a great trip. What is the time line you plan on? All summer or just 2-3 weeks? How much do you plan on driving in a day? There is just so much to do and so little time. lol. When we plan a trip I go to each state's tourism web site and order their visitor packet that we plan on being in. Research each city you are going through and see what is interesting to you. Outside Amarillo is Palo Duro Canyon State Park, the second largest canyon in the country. Might be a good place to explore for a day or two. Amarillo also has The Big Texas Steak Ranch restaurant. If you are inclined to have a good steak dinner I say do it there.

I would get off I-40 and follow rt. 66 at times too. Don't be shy about going a little off the I-40 route. Thats where you find the odd ball and quaint places you would normally pass by without ever knowing it was there.