If you're bored of cape town, why go a third time? Obviously, i think it's impossible to be bored of cape town as I'm originally from there! 
Madagascar seems like a crazy idea - it's an entirely different country and the flights and hassle would be huge.
what have you done in cape town before? What do you like doing? I'm sure there are loads of things you haven't done (or could do again).
If you are interestedin winelands, have you tried all the key regions? Franchoek? Elgin? Stellenbosch? Constantia?
If you want to get out of cape town properly, going up the garden route is lovely. Knysna, Plettenberg Bay, Sedgefield, Wilderness etc. Or go inland and do Okavango Caves, Addo Elephant Park, or other game parks.
Or go up the west cost - Onrus, Langebaan etc.
Do you want gorgeous views and interesting landscape? Or sophisticated eating and drinking? Different options for different preferences.
If you're willing to fly - Game farms north of Joburg - Kruger Park, Pilanesberg etc. Or go to Natal (not in SA summer - horrible) for other game options or a different beach vibe. Or the Drakensberg Mountains for gorgeous beauty, beautiful walks etc.