Check SeatGuru to see some airplane seat configuration for your dates, some are 2 - 2 - 2 while others are 1 - 2 - 1. Iberia is not bad, BA is the worst, then you have Air Europe which is good as long is 789, ITA too, then you have AF and KLM, which depend of the aircraft.

Add an extra day before your arrival, Atlas Cruises use charters flights, so they won't cancel which is great. Keep in mind Buenos Aires is a wonderful city (well, I was born there), but since you are in Ushuahia, you can expend an extra day there, then do Calafate (Big Ice or Mini Trekking on a Glacier is a must, but needs to be under 65yo).