I would also add lilliesleaf farm in rivonia. It was used by the ANC in the 60s and the raid here led to the treason trials. The museum and high tech exhibits have been built around the original buildings so you have a feel for what went on. It takes a few hours to take it all in.
We also were able to visit brenthurst gardens which is the Oppenheimer property but allows visitors into the beautiful gardens which are narrated by one of the staff and includes tea and biscuits.
I felt the same about sandton. Locals wanted to show us the casino and the malls. I don't want to visit either at home and certainly not on vacation.