John, the possibilities are endless.
My recomendation will be:
Spend 2 days in Capetown, there are a lot to see, trip to table mountain, the lighthouse museum, the waterfront, district six and the citys old buildings, and the fynbos world heritage site, asd well as Pobin Island

2 days on the wine routeand enjoy some of the RSA wines, Stellenbosch and suroundings is a must.

Carry on to Oudshoorn and visit the ostrich farms, you can even have a ride on the ostriches and visit the Cango caves.

Complete section with a trip through the garden route to George.

Fly to JHB.

Spend 2 - 3 days in JHB and Pretoria, there is a lot of history both old and young. Visit the Craddle of Humankind ( I was not part of that ancient history)wher fossils like mrs Ples was discovered.

Take a trip through the Waterberg biosphere, then tour up to Polokwane (Pietersburg) a lot is to be seen on the route with lots of interesting history. Visit the cultural village in Polokwane. Carry on to Musina and vist Mapangubwe, a recently discovered site of a ancien group of t people who lived there about 20,000 years ago. It is at the confluance of the Shasi and Limpopo rivers. take a trip through Kruger from the top to the bottom and exit at the bottom. Travel through the old eastern Transvaal and visit places like Graskop, Pilgrims Rest , Gods window, the three rondavels, various waterfalls, Bourkes Luck potholes and beautifull senery .

There is so much to do, I can keep you busy for two months never mind about 2 weeks. It is all about what you want to see and what interest you, nature, culture or history.