My husband and I are driving our 10 & 12 year old grandsons from our home in Tucson, AZ to the "family farm" east of St. Louis. Since they have never been on a long road trip, we'd like to go a scenic route with some natural wonders, maybe National Parks, along the way. The boys think their entertainment will be video games along the way but I'd rather they learn to love the journey. Suggestions for routes or sights to "wow" them?