We used Silverseas for the cruise and another travel agency for the rest. Ours was 18 days and we had the cheapest cabin. The cruise was about $19,500 per person. Flights another $4,000 or so to Santiago. However that includes everything, food and drinks and tips already paid. There are things I'd do differently, and some things we did well. I'll offer a few tips below.
-we stayed in the lowest cost cabin, and wouldn't spend more next time. For the cost of a "better" cabin they are not much larger, and you don't spend a lot of time in it anyway, think of it like a hotel room. If you can afford a suite go for it, but if not you'll be fine.
-it wasn't as cold as we thought, but we are from Wisconsin. We brought too many cold weather clothes, and not enough dressy clothes to save space. They give you a cold weather jacket and a waterproof bag for zodiac trips.
-we bought two new cameras for the trip, I'm going to sell one. Quite a few people only used their cell phones. Bring a spare cell phone if you have it, losing your phone during travel is devastating.
-they have a decent gym, bring workout clothes because you'll eat and drink a lot.
-there are shorter trips if you just want to say you went to Antarctica that avoid the Drake passage and are much shorter. However, it's once in a lifetime for most of us, so you have to visit the Falklands and South Georgia island as there is much more wildlife than Antarctica itself.
-bring Dramamine and cold medicine etc. on a small ship colds make there way around.
-if you are a single male traveler, these cruised have a lot of well to do single women on them lol.