Turner Falls and Chickasaw National get my vote. Great places to spend the day.

Chickasaw National Recreation Area (U.S. National Park Service)
Turner Falls Park, Davis, Oklahoma


There is also Alabaster Caverns in NW OK. http://www.oklahomaparks.com/detail.asp?id=1%2B5U%2B920 And stop by the Gloss Mountains on the way: Gloss Mountain State Park - Oklahoma Parks, Resorts & Golf


Take I-40 east to visit Heaver Runestone state park Heavener Runestone State Park - Oklahoma Parks, Resorts & Golf, Drive to the top of the World's Highest Hill (1999 ft.) in Poteau (hopefully they have cleaned that up). Then camp on the shores of Lake Wister. Heavener Runestone State Park - Oklahoma Parks, Resorts & Golf . In the morning drive the Talamina Scenic Drive to Robbers Cave: Robbers Cave State Park - Oklahoma Parks, Resorts & Golf