I have been to Carlton Centre a number of times (mostly related to work), and the boardrooms and offices on floor 46 have stunning views of Johannesburg. Yesterday afternoon, a colleague and I decided to stay a bit longer while the traffic died down, and went over to the 50th floor. It is named "Top of Africa" since it is the tallest building in Africa, and the views were absolutely stunning - especially as it was a pretty clear day.
While the view is stunning, I would think that a little more effort would be made to spruce it up more - and make it more visitor friendly. That said, there is a lot of floor space up there, and it is a lot more than other panoramas I have been to, making it easy to move around etc. Some effort is also needed to get some more recent information, and mark up land marks especially "new" places such as Soccer City.