Indian Cave near omaha, NE (i think), I have heard is great riding for the advanced rider/horse. very hilly and has rougher terrain. Never had a chance to make it out that way. Rock Creek Station near fairbury, NE is a good one but its near the kansas border. Very historical as it was a lay over for the oregon trail, and theres some wild bill hickock history their as well. I have ridden there many times and it has quite a few good trails for every level rider, and you could ride for days even though the park is about a square mile.