Moving from Las Vegas, NV to Ardsley, New York. We will be stopping in Fairview Heights , IL and Effingham, IL to visit family on the way.
ANSWER:
Sounds like an adventure! I couldn't resist MapQuesting your route. You probably already know how beautiful the red rock country around St. George, Utah is. If you're willing to go off the Interstates, you might consider taking the winding highways along the Utah-Arizona border. You'll end up going through the Navajo reservation and Four Corners. That's the route we took on a road trip from Fresno, CA to Belleville, IL a few years back. We ended up on US Route 54 for a long stretch thru New Mexico, Texas, and Kansas. Then back on the Interstate in Missouri.
But if you're going I-70, Denver and Kansas City will give you lots of places to stop and eat or sightsee. Also, we've got a page about the St. Louis Gateway Arch that might interest you: https://www.road-trip-ready.com/st-louis-gateway-arch.html
Hope you have a great trip, and thanks for posting!