Real bed pillow

Once you try it you will never go back to the horseshoe neck strain weak sauce

Those pain medications that make you unnaturally sleepy.

If you're flying internationally, look up to see if you get free alcohol.

I was stretching during my long flight and the flight attendant totally hooked me up multiple times with fun drinks.

Dramamine. Takes care of any motion sickness and makes you nice and drowsy.

When I flew intl I asked a doc to give me a prescription for two zanax (one each way) to be super chilled out and ended up asleep most of the way. Not sure if that's common, but I think it might be worth asking. Note: had we had an emergency landing, I would not have been able to protect myself, but that's because I mixed it with a bit of alcohol (which you should not do).

Silicone water bottles take up no space and travel well. Extra leg room seats in normal economy are usually narrower than normal seats due to the table and entertainment. Also no unseat storage, but it's less of a concern because once the flight is in air can just get your bag down.

I'm 190cm tall and 150kg. I just survived an 11hr flight on Turkish air boeing 777, following an 6hr flight on a Airbus a330 in economy on both. The Airbus was more comfortable. But Dramamine is your friend.

Sealed bag of cookies/chocolates/whatever as long as there are a decent number. Give it to whichever flight attendant is closest to your seat when you board. Most crews will have your back for the whole flight after that.

I just returned from a long trip and tried a couple of different pillow alternatives because showing in planes is so uncomfortable.

Get over of these.. it doubles as an eye mask and head support so you can sleep without linking your neck. SO much better than a pillow.

https://www.amazon.com/ORIGINAL-SeatSleeper-Travel-Support-Pillow/dp/B0758TY861/ref=mp_s_a_1_1_sspa