In Johannesburg, there are many restaurants ranging from Italian, to Thai, to Indian, to Chinese, to Continental, to Seafood.  A couple of 'newies' in the north are Tony's Spaghetti Grill just off William Nicol Drive in Fourways.  Busy, nice ambience and the food is reasonably priced and tasty.  Resident DJ on certain nights. 

Another restaurant recently opened is the Cape Town Fish Market (original obviously is in Cape Town!) - this is situated in the Lonehill Shopping Centre (which I heard aims to be the 'restaurant mecca of the north').  CTFM is a seafood restaurant, again quite vibey with fresh seafood second to none.  Prices are on the high side, but seafood restaurants in Johannesburg do tend to be on the highish side - maybe because we are so far inland!