We went to Cape Town last March (similar weather to October I think). We stayed 2 weeks in Cape Town.
We did a day trip to the Aquila Game Reserve, had a half day jeep safari and an afternoon horseback safari (they also do quad bike safaris). We were picked up at the hotel by minibus early morning, the drive the the reserve was about 1 1/2 hours. Lovely hot cooked breakfast and champagne on arrival and hot lunch later. You could drive there yourself, there were lodges available to stay in. Not sure of any age restrictions for children, but there were several there when we were, aged maybe 5+.
Beaches were lovely , but the sea is COLD. Boulders Beach was great for penguin watching - there were hundreds of them!
The trip on the cable car up Table Mountain was awesome and the view from the top, well, you could see for miles. My tip is do the Mountain on the first clear day you get, as it closes in fog/wind etc. You can book online on the Table Mountain site for the cable car and avoid the queue - we did that and you just choose a 2 week slot to go and can go any day.
Eating out in Cape Town was good, the V&A Waterfront has lots of nice restaurants. We also ate at Mama Africa's in the city - quite an experience!
The hop on off bus tour was good, ideal for a 'get to know Cape Town' day.
We also did a Wine Tasting day tour and a tour of the townships - both really good, but probably not suitable for a 7 year old!
There is a nice public open air swimming pool area with diving boards and sun loungers on the Cape Town promenade.