Johannesburg OR Tambo International Airport
Most people arrive into the country via Johannesburg Airport (although Cape Town is also popular). Both Terminals (A and B) have viewing decks to use, with B being the most useful for photography and catching all movements. The deck is indoors, with somewhat dirty windows, but you can always clean a patch.

The airport has a good mix of international and domestic flights coming throughout the day, so it’s rarely boring.

On the north and south sides of the airport are storage and maintenance areas. The north (Safair) can be mostly read from the viewing decks, but the south (Denel) can’t. Best bet is to hire a car and explore to make sure you catch as many aircraft as possible.

Rand
Another airport in Johannesburg, Rand is much smaller. It has a lot of stored airliners on site, plus the South African Airways Society Museum with types up to Boeing 747 in size. You have some views from inside the terminal, however it’s much more rewarding to organise a tour from the fire crews, which cost 20 Rand. These take in all ramps and areas of the airfield, so you won’t miss much.

Lanseria
This is a smaller airport to the northwest of Johannesburg. It has a number of airlines flying domestic routes, and is also a popular place to see bizjets flying  into the city. One the airfield are also a number of stored and withdrawn airliners.

You can spot from the viewing deck area which doubles as a food court. However, it’s also possible to arrange an airside tour from the security office if you contact them in advance.

Wonderboom
One of the airports in the Pretoria area, Wonderboom is an interesting little place. It is home to a variety of

aircraft, from safari aircraft to Boeing 737s; bizjets to historic flight DC-3′s. It’s possible to see quite a few aircraft from a circuit of the perimeter, however it’s often possible to arrange airside access from the security office.

Durban King Shaka Airport
The new international airport for Durban opened in 2010, replacing the existing facility. It is actually over 20 miles from the city, but is ultra modern and one to watch for the future. At the moment it handles close to 5million passengers per year, with a mix of domestic and international. There are viewing opportunities from within the terminal.

The airline has announced the routes the aircraft will operate as:
Dubai (1 February 2010)
Johannesburg (early 2010)
New York JFK (23 November 2009)
Tokyo Narita (spring 2010)

All will operate from Paris CDG airport. Interestingly, the route to Dubai will start 15 days before Emirates start using A380s on their Dubai – Paris route.

The aircraft will visit Paris Orly on 11 November to test the airport as a diversion field from CDG.