If you want to visit a real ranch, you might try looking for Bed & Breakfast lodging. I'm sure that some of those are ranches, and it is also a great way to interact with the people along the way.

I agree Midwest Michael about the Henry Doorly Zoo in Omaha. I lived in Omaha for 6 years and have been many times. The Oklahoma City Zoo is also quite nice if you are anywhere near there on your trip.