Drake Passage can be ROUGH. We did it earlier this year and had the worst possible conditions on the way back through. It bucks you like a bronco, even in the big ships.

Highly recommend stocking up on Meclizine to prevent seasickness. I get seasick very easily, but wasn't even nauseous once thanks to those miracle pills. Unlike about 50% of the other passengers that day! Meclizine is OTC and available on Amazon.com, and works way better than any other pill I've tried.

Also highly recommend an excursion to Punta Tombo (Argentina) if you're at all interested in seeing penguins up close. Literally, up close - they will hop right by you as if you weren't there, and there's about a quarter of a million of them all in one spot. It was a real highlight for us: https://en.wikipedia.org/wiki/Punta_Tombo

If you do the Falklands, everyone raves about Volunteer Point - book that one early because it always fills up fast.

For Antarctica, invest in an ultrazoom camera so you can really see/capture the wildlife. We got so many shots of a lifetime during our 3 days there. Also invest in proper cold weather clothes (jacket, gloves, hat, scarf) so that you can enjoy the outdoor scenery as long as possible in potentially 10-20 degree weather. I wore one of these furred trapper hats with ear flaps and was perfectly toasty outside for hours on end - really made a huge difference: https://www.amazon.com/Kurhatic-Trapper-Aviator-Russian-Trooper/dp/B0B7ML7C3Y