Bear Butte is part of a State park, so there is an entrance fee if you don't have a SD Park Pass. There is an exemption for tribal members; just have proof of enrollment and it's free.
A well-established and maintained trail leads to a wooden viewing platform at the top. Stairs lead up the final few yards. It is steep in places, but the improvements keep the hike easy. Prayer flags are everywhere, as many tribal members come here for their hanbleciya (vision quest) or just to offer prayers. Wildlife is abundant, sometimes subtle, but ever present. Bison roam at the base, deer hide among the trees near the base, hawks and eagles are frequently circling above. There is a sense of other-worldliness to this trail; it is the closest thing I can imagine to a natural cathedral. (YDS Class 2: improved trail)