Ausable Chasm, New York
"The Grand Canyon of the East" has been open to the public as a tourist attraction since 1870. It's more like a mini-Niagara Falls than a Grand Canyon, with twisty trails that take you down into the gorge past lots of evocatively named rock-and-water formations: The Devil's Oven, Sentinel Rock, Elephant's Head, The Flume, etc. This place was nearly destroyed by two "once in a century" floods that struck within 10 months of each other in 1996, but it seems safe now. You can raft or tube or kayak through the gorge. We thought that "ausable" was something between "awesome" and "audible," but instead it's "au sable," French for "sandy." The Chasm is a popular spot with French-Canadians.
The official guidebook, still for sale in the gift shop, was written in 1942.
Not particularly amusing from a roadside perspective, but stop if you can spare time before racing to the ferry to search for lake monsters.