Capetown, South Afica

Some things to consider. 1) visit Table Mountain but make sure it is a clear day - it’s the only place I’ve encountered a cable car that rotates 360 degrees while it is traveling. Also pay attention to the plant life at the top which is unique in the world. You could hike it up, or down like we did but it is very hard on your knees even if you are used to significant elevation changes
2). Rent a car or hire a driver to go to the Cape of Good Hope including stops to see the penguins and some of the towns along the way. When we did this we saw whales, dolphins, and baboons just from the roadside.
Another common excursion is to the wine region if you are so inclined.

The Kirstenbosch Gardens are lovely with lots of native plants and flowers and birds.

If you like history, you might consider taking the ferry to Robben Island. This is where the prison in which Nelson Mandela was imprisoned is located. Guided tours will take you around the prison complex and the grounds. The drive around the Cape is beautiful. If you do this, stop at Boulders Beach in Simon's Town to see the African Penguins. As noted previously, the botanical garden is very nice, and Table Mountain is awesome if it is a good day weather wise.

Table Mountain has fantastic views and it’s a nice place to walk, so it’s a good choice if you enjoy scenery and hiking.

The drive down to the Cape makes a wonderful day trip. The scenery is stunning, and the penguins are adorable.

I did not do any safaris in South Africa, but if you can find one that’s a reasonable distance and if you’ve never been on a safari, I would make that my first priority.

Agree with above posters, except instead of Robben Island, I would take a tour of District Six. The whole neighborhood was moved because white folks decided they wanted to live there.

I found the tour of Robben Island very interesting. I was there 20 years ago and my tour was led by someone who had been imprisoned there during apartheid. As 20 years have passed, I suspect that has changed due to the age of those imprisoned.

I took a tour of the Cape Peninsula which included a stop at Boulders Beach to see the penguins and a stop at the Kirstenbosch Botanical Garden and really enjoyed that day.

A safari would be a great choice, but you will have to travel away from Cape Town.

Just offering an update to the post above re Robben Island. We were just there in August and our tour group was led by a man who had been imprisoned there. He was able to give very interesting insight on what it was like to have been there.

I was in Cape Town February of this year. It was overall a great trip and since its summer in that half of the planet weather was amazing.
One thing to be aware of is the situation with power cuts; the locals call it "load shedding". Every single day there will be power outages at different times for around four hours. The hotel will give you the bizarre schedule. I was aware of this before my trip and had mixed results with it. It didn't effect my sightseeing as most touristy places had backup generators. But my hotel didn't, and while loss of electricity wasn't a big deal, I hadn't considered the loss of running water which was the bigger hardship. This meant no showers and backed up toilets. In addition WiFi would be out longer than the blackout as it took a while to get the network going after power was restored.
Also consider visiting some of the fishing villages on the outskirts of the city like Kalk Bay. Which has great laid back vibe with good shopping, and restaurants like Kalky’s which has a reputation for the best Fish & Chips in the world. In neighboring Simons Town I highly recommend a boat excursion to Seal Island which is a big rock in the middle of the ocean where there are hundreds of seals frolicking at any given time. (https://www.boatcompany.co.za/seal-island-eco-cruise/)
Back in the city center the Victoria & Alfred Waterfront area while being very touristy is well done and worth a bug chunk of your time. The highlights for me the lots of upscale restaurants, Zeitz Museum of Contemporary Art, Aquarium,and the Watershed Pavilion with local arts & craft for sale. Weekend mornings consider the Oranjezicht City Farm Market which is a great place for brunch with a large selection of food stalls. It's very popular with the locals so try to get there as early as possible to avoid the crowds.
There are lots of hotels at the V&A but were too pricey for me so I opted for a hotel in the Kloof Street district near Table Top. It's an upscale neighborhood with lots of good restaurants and smaller hotels.
For transport I took Uber everywhere, rates were very cheap, and service plentiful.

p.s. also be sure to check out Truth Coffee Roasting. It's a funky coffee house in the city center with a reputation for have the best coffee in the world. Coffee aficionados worldwide travel to Cape Town specifically to indulge in their coffee.

Robben Island. We were just there in August and our tour group was led
by a man who had been imprisoned there.

By law the tours have to led by one of the former prisoners. While this of course enhances the tour, it also means cancellations of tours when they are not available. Which happened to me twice during my stay:(

Take a day trip (along Chapman's Peak Drive- beautiful!) to the Cape of Good Hope, Simon's Town and nearby Borders Beach (penguins!). We also stopped at Kirstenbosch Botanical Gardens to walk the marvelous tree top bridge. We stayed at the Spier Winery near Stellenbosch. They have a beautiful lake, a bird rescue, and a fun Segway tour around the winery.

These are all good suggestions. South Africa is a lovely country and absolutely delightful; spend as long as you can. My biggest recommendation is purchasing a ticket on the Hop On Hop Off (Red Bus). This functions lovely in Cape Town and takes you all around the smaller peninsula. You'll definitely want to make it around Chapman's Peak Drive and maybe to Simonstown if you would like a quaint area -- You don't have to purchase tickets to the Nature Reserve in Simonstown to see the penguins; they will be around when you get close to the beach! As other have noted, if you are interested in botanicals, stop by Kirstenbosch Gardens. Cape Town represents a unique botanical biome found no where else in the entire world (fynbos) - also makes good gin which I am sure you will find in the winelands. I would recommend taking the Wine Tram if you want to explore the winelands around Franschhoek - not sure where you are staying. Nevertheless, Franschoek is a lovely area. You will be subject to loadshedding (power cuts) but where you stay can advise you one the schedule of this (which may or may not be accurate - Cape Town is typically better than the rest of the country in this regard). Others have noted well the benefit of history lovers visiting Robben Island; however, the weather will dictate if you are able to make it to the island. Cape Town weather is absolutely lovely, but unpredictable. If you want to make it up to the top of Table Mountain, your schedule should be guided by the weather - if it is a clear morning when you wake up, go to the mountain first.

The V&A waterfront is a nice area to relax and has some nice restaurants and live music typically in the evenings. There are some nice restaurants along Mouille Point and Green Point area (not far from V&A Waterfront). Ubers are, in my opinion, are quick, safe, and affordable (Lyft does not function in SA). All of this said, the Hop on Hop off Red Bus is lovely and will even take you to some of the larger wine estates (Groot Constantia is nice). The areas serviced by this bus service are more than enough to fill your several days prior to the wedding. The views on the open top of the bus are divine. Of course, it being summer, bring your hat and sunscreen and sit on top of the bus; the Atlantic Seaboard is a beautiful sight as you wind along the roads! Enjoy! Happy to make other suggestions if you need more specifics!