Road Trip!

So, I have decided to surprise the husband with a road trip.  I am pretty much going to wing it however, if anyone has any ideas of activities along the way that would be fabulous!!! Please leave your ideas as a comment.  We will be leaving from Saint Louis, MO and traveling toward Elizabethtown, KY.  I am looking for ideas on:

• Fantastic places to eat
• Cheap places to stay
• Fun activities to do outside
• Must see attractions

We would be up for going off track a bit if it is an absolute must see!!  My goal here is just a totally relaxing detox kind of last minute road trip.

Shhh don't tell the hubster, it's a surprise!!