Cape of Good Hope is an exciting place to visit. But if you're already there, don't miss a Bus-trip to Cape Point. the point where Atlantik and pacific ocean meet.
There are lots of Tourist guides offering cheap Bus-Trips through all local Attractions, incluting Cape of good hope and Cape Point.
Usually that's a full day of Sightseeing-trip for approximately 30-50US$.
Mostly entrances are also inclusive.
At Cape Point there is a beautiful restaurant with a perfect view. You HAVE to go there. Isn't expensive anyways.