Since your kids are a little older, and may get into the "high speed automated manufacturing" thing, you may consider a tour of the Anheuser-Busch brewery. I will apologize in advance if I offend with a beer suggestion.... but, it is a free tour and is amazing to see the process - whether you drink or not...
Actually that is on our list. I didn't want to offend anyone either
I went as a kid to the one in Florida, so I thought my kids would enjoy seeing how they bottle it and make it.
"Actually, I was going to suggest a sports activity for the boys to do, if you're OK with it. (You can do it, too, if you like; it's not a kids-only thing.) It's my 13yo DS' favorite local special activity, and has been for a couple of years now. There is a SkyZone jump gym in Chesterfield, and it is open in the evenings. There are not too many of these gyms in the US; they are kind of unique. A short session (30 minutes) is $8/pp. Longer sessions cost a bit more.
http://www.skyzonesports.com/default.aspx"
This looks like fun too! How busy do you think it would be on a Sat afternoon/evening?
Thanks for the advice about staying in Chesterfield. I couldn't figure out what everyone meant by I-64 and had to head back to the map. I just kept remembering that we would take I-70 straight thru IL & MO. I'll be looking up the Drury today.