We had a lovely stay at The Cape Colonial. The owners helped us with transfer from and to the airport, and gave us some great tips on restaurants and shops in the neighbourhood. Our room had high ceilings, lots of room, a big comfy bed and, best of all, a nice balcony where we enjoyed our tea and muffins and banana bread in the mornings, and some snacks and drinks (buy your own at the local supermarket) in the evenings. There is free WiFi and some books to borrow while you are there, and we also got a free map of the city to help us find our way.
The guesthouse is at an easy walking distance to the Company Gardens, the National Gallery, Greenmarket Square and Bo Kaap, and we had no trouble getting around. We'd definitely stay here again next time we come to Cape Town!