Tennessee's Rock Island State Park
This park is located on the Caney Fork River, near Rock Island, TN. The Great Falls Hydro Plant of TVA's is right in the middle, and the dam is right at the entrance to the park. See the Great Falls Dam page for more information about that project, which you gotta see while you are there.
We haven't actually stayed at this park yet, but hope to soon. Besides the hydro project, this park promises some good hiking trails and birdwatching. This park has a naturalist on staff, and has some interesting displays in the office. We can't comment on the cabins yet, but all of our experiences in the Tennessee Parks have been good so far.