I can't believe I'm recommending this, being a Bose-hater for most of my adult life, but the Bose QuietComfort 25 Headphones are now my favorite travel accessory. Overpriced, yes. Average-ish sound quality, sure. But the noise canceling is uncanny. Flip the switch and the silence is surprising. Unlike most other noise canceling headphones I've tried, these don't give me a headache. I've used them on a few long haul flights at this point (17-20 hours in the air each trip) and they're comfortable enough that I sleep with them on.
The Sony noise canceling headphones I used to own would give me a headache on a cross country flight. They were so annoying (and others I tried so poor at canceling noise), that I switched entirely to passive noise cancelation, using IEMs that just blocked sound.
That worked well enough, but on these long flights, enough noise gets through that my music needs to be loud enough that the music ends up giving me a headache after 5-6 hours in the air.
So, consider me a convert. If you have to fly as much as I have had to recently, these are worth the investment.
They work really well in the office, too. I'll still use my PSB M4U 1 there, because the sound quality is better and I have an office with a door. :)