Categorized by region, but in no particular order…

Somerset West
Morgenster—lovely olive oil and wine tasting (three bordeaux style red blends).
Vergelegen—the wine tasting was impersonal with a la carte pricing but the beautiful estate and gardens made up for the lack of charm.
Wellington
Diemersfontein—the most delicious chocolate and coffee pinotage! The wine tasting room closed seven minutes before we arrived, but the service staff allowed us to hang out on the patio and order a few glasses of wine and enjoy the sunshine. This was by far the best pinotage of the trip.
Hex River Valley
De Doorns Co-op—mix of wines from the local wine growers, the best was an unusual Viognier/Shiraz blend from Auction Crossing.
Constantia
Groot Constantia—huge place, very touristy, but they have some decent wines and a good port.
Buitenverwachting—we tried a sauvignon blanc from here in NY before we left and when we asked about it, the woman had no idea what I was talking about. Regardless, we really liked the dessert wine. {see update below}
Darling
Groote Post—charming place, the best wine was the Old Man’s Blend red.
Ormonde Vineyards—nice sauvignon blanc, but we decided we aren’t big fans of bush vine grapes in general.
Darling Cellars—forgettable.
Cloof—nice shiraz and pinotage but the guy was rude and that can be a dealbreaker for us. {see update #2 below}
Worcester
Nuy—good wines, a very nice dessert wine, but the woman pouring seemed to have no knowledge or interest in the wines.
Stellenbosch
Spier—not impressed with the wine, but the buffet lunch at Moyo restaurant and cheetah exhibit were great.

Update: Because the internet is an amazing place, we just received an email from a US importer for the Buitenverwachting winery in response to this post. The wine we had in NY was the ‘Beyond’ sauvignon blanc and we liked it so much, we made sure to visit the winery on our trip. Apparently, the same wine is called Buiten Blanc in South Africa; it was renamed for distribution here because of the possible trouble pronouncing Buitenverwachting in the US. She also forwarded our comments to the winery, so they are aware of the alternate name. (Thanks Molly!)

Update #2: We also received an email from Cloof asking for more information about our “rude” host, so we let him know the exact date and time we visited the winery. Frankly, I feel the guy’s attitude directly stemmed from the fact that the winery closed at 4pm and he had little interest in helping us because we walked in at 3:40pm. My dad purchased some wines (simply because they were very good), but as soon as we walked out the door, it was shut and audibly locked behind us. I hope the man who contacted us looks into this matter and am glad he wrote asking for a follow-up.