I'm always an advocate of Cape Town of course, but if you really want to scare yourself **less, head here anytime between November and March and try kiting away from the usual world class spots of Table Bay (which can be ** scary themsleves some evenings when it's blowing a steady 35knt+).
Depends on whether you want big waves or not, but try Cape Point if you're feeling brave enough. Pretty treacherous coastline not for the faint-hearted with some pretty huge swell. It's basicall the first point the famous Cape Dr SE'er hits land and is where the Atlantic and Indian oceans meet. Pretty daunting place to visit out of the water, nevermind in it! Oh, and shark activity is far more prevelant this bit further down if that tickles your gung-ho fancy LOL!
You'd probably be advised to seek advice and/ or hook-up with one of the kiting outfits in Table Bay who do trips down there for the crazy folk. It's about 85km south of Cape Town.
e.g
www.kitekahunas.com/kitesurfing_cape_point.html