Ah yes, I did leave out Missouri and Maryland. We're from Utah, so don't plan on doing much exploring while passing through there, just visiting with family.
Yes, we will be traveling mostly on I-70, but have no problem getting off of it a bit. I've heard good things about Branson, so that would be a fun one to put on the list.
A tentative route is UT, CO, KS, IL, IN, OH, PA, WV, DC, and on the way home PA, MI, IN, IL, IA, NE, CO, UT
We plan on around 17 days, but our schedule is flexible. We have 4 kids, ages 7-13, but do enjoy hiking and sightseeing. I'm interested in any quirky things too, like "World's Biggest Ball of Twine" sort of things, just because they make me laugh. Not too big on museums, unless they're kid-friendly.
We will be hitting as many sights in DC as we can once we're there, but I'd like to have some ideas of places we can stop along the way. Also, if anyone has boondocked in any of these states and can give good recommendations, that would be great too.