Robben Island definitely worth visiting, we even saw little penguin in addition to the historical sites. The sunset on return boat trip, shining over table mountain and onto the water, was spectacular.
Also the Township tour. The van's we had were driven by a local township husband and wife team - pleasant and informative. We visited a local house and a couple of the very small rooms. One of a single man, one of a family with 2 children. We also walked extensively in the township streets and compared the renovated flats side by side with the unrenovated ones.
I though the Stellenbosh tour was a waste of money, but then, I went more for the scenery than the wines. The country wasn't as spectacular as I was expected, more pretty rolling hills that I could see at home. We did have a marvelous lunch in a very interested building. Then about 4 wine tastings in different vinyards - they were interesting. All red wines were chosen by out guide,, none of which I liked (but the 'red' wine lovers did - I prefer whites). Our tour guide talked softly and was very hard to hear. We wandered around town awhile. To be fair, the others enjoyed the trip more than I did.