This is frequently cited as one of the best botanical gardens in the world and if you visit you will see why. The setting on the edge of Table Mountain National Park is unbeatable even when the table cloth is rising and falling.
The easiest way to arrive is to take the "hop on hop off" city tour bus. This allows you to enjoy some wine tasting on the way back to Cape Town. Don't miss the coral trees, the protea garden and the recently-installed treetops walkway. Plus if you are peckish the cafe at the bus stop entrance serves English cream tea.