I've been to South Georgia (and the tip of the Antarctic peninsula) but, unlike Shyheels, only as a tourist. Truly incredible places. One special memory on South Georgia was seeing a colony of king penguins. Said to be over half a million individuals, adults and furry brown chicks. Penguins further than the eye could see.
We also landed on Elephant Island which is very rare for a tourist trip. That was on the opposite side to where Shackleton made camp. We came close to the site of Shackleton's camp, and also the monument, while in a zodiac.