During our lengthy layover in Johannesburg between our South African Airways flights from Dar es Salaam and New York, SAA gave us a chance to try out the Cycad lounge in the O.R. Tambo International Airport, which is normally reserved for first class customers (SAA uses a two-class system on most of its flights, but recognizes connecting passengers flying first class on codeshare flights), Voyager Lifetime Platinum and Platinum members.
If your clients have any kind of layover in Johannesburg, see if you can book them into Cycad. There's nothing wrong with Baobab, of course, but those extra little touches can make a world of difference.