Just a word of warning: If you are ever traveling through Kansas on I-70, don't stop at Russell, KS at a campground called Fossil Creek RV Park. It is a dump!!!
Also, there is one in Scotia, CA called Stafford that is about the same. They are both Passport American Campgrounds.
This past July we stayed one night at the KOA in Wakeeney, KS. It was a good place for an overnight while traveling through. The personnel were great. It appeared that they are mainly a one-nighter RV park because they were nearly full that evening but were almost empty by 9 AM the next morning. If you are going through during peak travel times you may want to call for a reservation.