Historic places to visit such as (1) Die Kasteel - the Dutch Fortress dating back to 1652 , must see places of interest such as Robben Island (Nelson Mandela was imprisoned on Robben Island), visit Table Mountain by cable car, go for a beer at the Waterfront, visit surrounding areas (winelands - visit wine estates, wine tasting), experience local cuisine - Cape Malay food, go for a West Coast trip to Velddrif, Paternoster and Lambertsbay (eat at the Muisbosskerm - traditional food - fresh seafood (fish, lobster, abalone).
Kruger National Park
If you fly in to the Park, not much to do except go on a game drive in the morning and a game drive in the afternoon - after that barbeque and drinks
If you drive up, then it is a different story depending on your route about 5 years ago
Andre above gives great advice.
I was in CapeTown & Kruger July-Aug 2012 (+ Namibia) and loved it. Happy to answer any questions.
Great food in Cape Town - make sure you go to the Victoria and Alfred Waterfront to wander and eat something wonderful. Try the biltong for a snack!
There are great day excursions out of CapeTown : penguins, Cape Point (you'll see ostrich, baboon, various antelopes), wineries (Stellenbosch is lovely university and wine town).
You can be out all day in Kruger on safari, but best animal viewing is dawn and dusk. You'll want a midday nap! And the sundowners are delicious :-)
I have some advice here: https://traveleater.wordpress.com/category/africa/
on two luxurious stays in Cape Town and near Kruger, plus advice on essential packing for a safari (for Namibia, but same rules apply).
Safari murzi! about 5 years ago
In Capetown visit the wine country, the Gem Factory, ride the little railway around the Cape, go to top of Table Mountain, take a trip to the Cape Reserve, take the train or fly to Jo,burg and then rent a car to go to Kruger. Rebook Kruger for sure. Take a night safari one evening in Kruger.
Accommodations are very good in Park. Book different camps as you travel through. almost 4 years ago