It's too bad only KLM offers a day flight on the longhaul from Europe to South Africa anymore. We flew it on Swiss from ZRH several years ago. The impossibly thin band of green along Libya's Mediterranean coast and then the vastness of the Sahara was stunning. The Sahara itself was beautiful, too... almost lunar, endless, featureless, except for giant mountains rising out of nowhere and tiny straight-line roads barely keeping the sand at bay. By the time we crossed the equator, it was twilight, but we could see giant thunderheads in the distance, lightning crackling around inside the huge clouds. What a great introduction to Africa.
David