Definitely do a trip to Robben Island, and if you can see if you can do a day trip to the wine regions of Stellenbosch, or Franschoek, when we were there our hotel ran day trips so we didnt need to drive, we had our own private driver and it cost us about € 100 between us for the full day, that included entry to 3 different vineyards, it was well worth it. He did a mini tour through the shanty towns on the outskirts of Cape Town on the way back to the hotel, which was very interesting although definitely a sobering experience!
Weather should be good in November so if you want a day at the beach its worth the taxi fare out to Camps Bay, fabulous beach about a 20 min drive from the city centre, again our hotel had private taxis we could hire, from memory it was about € 20 taxi fare, worth it if you plan to spend the day there.