Areyou, yes I mean our winter as in June. Mauritius and Reunion have no malaria, but Mozambique does, I hadn't thought of that although the risk of malaria is greatly reduced in Winter. There are some very good anti malarials these days with little in the way of side effects.
Both Mauritius and Reunion are french speaking, but it will be very English based. There will no doubt be lots of South Africans on holiday there, which is a positive or negative depending on how you look at it!!
In June, Cape Town is beautiful, its called the green season but is rainy. Upcountry has rainfall in summer, not winter so is very dry in June and is a fantastic time for game watching because the grass is dry and low rather than green and high, so visibility is much better iyswim. The days will be sunny and clear, T-shirts in the day etc, but cold at night.
And also, the Kwazulu Natal coastline is beautiful - very tropical, white sandy beaches. There is a fab resort called Rocktail Bay that's worth a google.
So I would recommend, 5 days in the Cape - penguins, winelands, table mountain etc; 4 days on safari (3 is actually enough and it is expensive) and then something like Rocktail bay. If your budget is very generous, you could check out a game reserve like Phinda, also in Natal. If you have a bit more time you could do Mauritius or Reunion (5 hours flight direct from Cape Town/Jhb) so is an easy trip.