If you were not familiar with this sculpture, the Crazy Horse monument is a 60-year-old work in progress. Construction began about the time Mount Rushmore was completed, but received less fanfare and support. Plans are still alive to complete the likeness of the Lakota chief on his granite steed.
There is nothing in Wind Cave in terms of scenery or wildlife that you did not already see everywhere outside the park. Buffalo, pronghorn, prairie dogs and coyote are familiar ambassadors to these environs. North of this tiny national park begin the granite towers where America's foremost sculptors have carved more meaningful attractions, starting with world-famous Mount Rushmore, probably the single motive why travelers pass through this park.
Most of the attractions in this part of the country are taken in turn, but they are spread out among the western counties of South Dakota and the eastern edges of Wyoming. If you are stopping at Wind Cave, there is no reason to miss the chance to visit Devil's Tower north of Sundance, Wyoming, the westernmost site generally included in a tour of South Dakota's Black Hills.
In Hot Springs, South Dakota, south of the park and Mt Rushmore is a museum or attraction known as the "Mammoth Site," which claims to have a few dozen giant mammoth remains.
I did not stop in, so I can offer no testimony to its worth as a stop.