Johannesburg

In terms of the weather there is not really a best time to visit Johannesburg. Daytime temperatures are fairly warm all year round, with the high altitude keeping summers from getting too hot. The South African winter is between May and August, and if you plan to take safari then the lack of foliage at this time makes it considerably easier to spot lions!

Johannesburg is not as dangerous as you might think. Crime is nowhere near the level it once was and you'll immediately notice cars stopping at red lights all over the place without being stolen! Like any city, crime is still an issue but tends to be particularly high around certain areas. Avoid Yeoville, Berea, Hillbrow, and Alexandra if you can, and opt for taxis over public transport, which is quite chaotic.

Johannesburg is a city of suburbs, so don't expect a hotel in the center to be your best bet. Consider booking a guesthouse in Melville, Sandton, or Rosebank. For contrast, Soweto is the city's largest township. Although it's still quite poor, it's one of the friendliest, liveliest parts of the city. The downside to that is it can be hard to get any sleep!