Let KAYAK do the searching
Based on KAYAK hotel searches, the most popular destination is Rapid City (44% of total searches to South Dakota). The next most popular destinations are Deadwood (38%) and Sioux Falls (13%). Searches for hotels in Keystone (5%) are also popular.
KAYAK users have found double rooms in South Dakota for as cheap as C$ 61 (Deadwood) in the last 3 days. The average price is C$ 223.