I always stay in 10 2nd ave Houghton Estate when I go to Johannesburg, i.e. more than 20 noghts per year. It provides all the services you normally find in a luxury hotel. It is professionally run, there is always a manager, chef,waitors and someone at housekeeping.
They are extremely friendly and prepared to go the extra mile. Eg. Although they have a good al la cart menu, the chef is always prepared to prepare a special dish on request.