Those really long haul flights are starting to take it out of me, last November I went with Etihad from Brisbane Abu Dhabi Manchester all in 787-9's 2.5 hr layover in AUH
on the 14 hours BNE AUH the supposed higher humidity and lower altitude pressure didn't seem any different to me at all, I got off at MAN totally stuffed, kind of normal
On the return I had a 777-300 from MAN to AUH them 787-9 to BNE, deliberately tried to notice the difference between the 2, couldn't feel anything.
the real downside seems to be the 787-9 is not the right size of aircraft for the market, it's just too small, or needs double the frequency, and try getting those slots at Heathrow now, given that they once had them but sold them off.
Another super long haul was tried by Singapore Airlines with Airbus A340-500's doing Singapore to New York non stop in about 18 hrs.
https://en.wikipedia.org/wiki/Singapore ... _Flight_21The problems are how many pax do you want to carry, the accountants say as many as will fit, the pax want more space, the accountants usually win the first round until sales go downhill which is what happened to SQ, but then they started with very generous seating arrangements.
the long haul non stop flight sound great, but until they can do it much faster it is not such a great idea, we need more Mach 3+ airliners booming their way over Russia.