Peninsula day: (You will need a full day for this!)
Drive via camps bay to houtbay - take the seal island cruise
Drive to Cape Point (where the 2 oceans meet) and walk up to the lighthouse on top.
Drive to Simons Town (Boulders Beach Penguins)
Lunch at Two Oceans Restaurant - good food!
Cape Town City tour:
Visit the cape malay quarters, visit table mountain, lunch at camps bay - summerville or bayside cafe
Afternoon go to the waterfront and explore, and then Robben Island
Winelands:
Drive to Stellenbosch - visit Spier, and some wine estates. Drive to Franschhoek, wine estates, Boschendal's Picnics are very good, and so is the wine.
Id stay away from townships, unless you have a qualified guide, that has passenger liability.
Other than that, you can go to Greenmarket Square, Blouberg, botanical gardens, llundadno etc.
Really alot to do, just plan each day - so you dont drive up and down to much
Enjoy your stay and be safe!