I fly internationally all the time, most often in Business class, but I have gone steerage – I mean coach – LA to Sydney (as part of a trip starting in Boston). It sucks.
Since I normally have to work (in front of clients) on the other end, sometimes within hours of stepping off the plane, getting sleep is essential when crossing timelines. I find I can’t sleep nearly as well unless the seat is horizontal – not flat, as some airlines advertise, but horizontal. But I can get that in Business Class on a few airlines now.
I also find I would rather take any major non-American airline over any domestic US flight. US airlines have become crowded, dirty hellholes with poor-to-awful customer service where you get nickled-and-dimed to death for every minor amenity. Croatia Airlines is better than almost anything flying in the continental US today, and I’m not kidding.