we also just got back and took the same advice as RN.
stayed away from keystone but took the drives thru the wild life loop and got right up to the buffalo.iron mountain and needles were awesome drives.went out to the badlands for a day,thats not to me missed.
the 600 mile drive each way, back and forth to Minneapolis is a hassle because its a long drive but there is no way to stop for the night because home would only be a couple hours more so you may as well push on and get it over with.