I think the key is probably to mix things up, don't just go for fabulous majestic views, but include cultural stuff in there too. Visit historic towns, museums, even festivals. Try the regional foods, take a Barbecue tour of the southern states and see how the flavor changes from the Carolinas with their mustard BBQ sauces mostly on Pork, across Alabama with their sweet BBQ, and on into Texas with the Tangy BBQ which is almost all on Beef, in between stop off in south Louisiana for some real Cajun food, not that Creole mash up stuff the sell in New Orleans. While you are at it stop to see various bits of Americana along the way, go to the Car Collection museum in Kearney Nebraska, tour the Vicksburg civil war battlefield in Vicksburg, Mississippi, take a relaxing (or not so relaxing) float trip down the North Platte River in Saratoga, Wyoming depending on the season.
There are so many places to explore, and many of them hidden away around the country in places you would not expect to find them, like the National Pacific War Museum in Fredericksburg, Texas ( a small town about 75 miles west of Austin in the Texas Hill Country). Who would expect a museum that can take days to tour to be located in a town of 12,000 people in central Texas, the basic ticket is a 2 day pass for a reason.
The list goes on and on, but as I said I see the key is to mix it up, stop in to see that worlds largest ball of twine, or when passing through (or near) Hutchinson, Kansas catch both the Cosmosphere space museum and the Startica salt mine museum where you actually descent nearly 650 feet below ground to tour a salt mine.