Robben Island/Table Mountain Timing
It took me three days to get to top of Table Mountain due to weather. The hotel concierge reserved my ticket so I could skip the ticket queue. I ended up having the day tour from the wineries drop me off on way back to watch sunset which was incredible and not that crowded. Downside was that I had limited time so couldn't hike out much. But it was so worth it (photos on my blog - same as user name)
Robben Island ticket was booked in advance.
If you get great weather and water you should be able to do same day.