I second for temazepam. It takes me about eight hours to sleep it off. Take it after dinner and sleep to breakfast when they turn the lights down.

Temazapam works for about two hours for me then I am awake. I take Stillnox and sleep 7-8 hrs.

If I have an aisle seat, often do due to my knees, I tell the people next to me just to climb over me, no problems!

Of course I much prefer it when a company/client pays business class
If I can swing it I try daytime flights, obviously not for really long-haul distances though.
Cheers, Chris