When I was checking into my lodge in Jeffreys Bay, the check-in guy was on the phone with a car full of surfers who were en route, same day from Cape Town because they heard big waves were expected, so you can probably get from PE to Cape Town in two days of driving. Of course, you're better off just flying PLZ to CPT at that point, if all you plan to do is drive non-stop. Besides Addo, my personal highlights between PLZ and CPT were De Hoop and Swartberg Pass (I also liked the small town of Prince Albert on the other side of the pass from Oudtshoorn), very scenic but demanding drives. This would mean four days of driving at a more leisurely pace.

I loved Cape Town and don't regret spending six days there. Weather was a bit unpredictable, so I didn't do everything I wanted to, but you can easily fill up a week based out of Cape Town. If you want to visit Robben Island, book that first, as they do cancel ferries if winds are too strong. If you want to hike up Table Mountain, try to avoid the weekends, and bring plenty of liquids. An early start is also a good idea; otherwise, you'll be too rushed. I read a "three days in" travel article a few months back, and the writer claimed to have seen everything I saw in and around CPT in three days. Perhaps he did, but most likely he didn't.

I didn't have time to visit any of the vineyards, but I think Cape Point is a must visit outside the city (I also went to Cape Agulhas which was a complete waste of time and effort). Don't bother paying for the funicular up to the current lighthouse, just walk up, it takes 10-15 minutes, and hike down to the original lighthouse if you have the time. It's a massive national park and you can easily spend an entire day there, hiking and driving around. Pack a picnic lunch though because food options are limited.