How it actually works
There is no short way. Routing is via a Gulf hub or via Africa, and you land in either Johannesburg or Cape Town — which one you land in should be decided by the itinerary, not by the fare, because getting that backwards adds an internal flight and a wasted day.
The classic shape is safari first, Cape Town second. Doing the wildlife while everyone is fresh, and the city and coast when they are tired, works far better than the reverse.