For trans oceanic in econ, I bring some combination of these choices: Nut/Chocolate Trail Mix, Beef/Turkey Jerky, String Cheese, ziplock with some slices of salami or roast beef, ziplock of triscuit crackers. I also bring half a dozen paper napkins.
And then if I'm feeling really trashy: I buy a McDonalds McDouble and wrap in saran wrap. It's my secret travel vice.
In general, I choose protein over carbohydrates (the chocolate not withstanding). Since I won't be physically active, I don't need instant energy. I just want to keep my blood sugar nicely balanced. And I don't want things that are messy to eat (pizza, vegetables and ranch dip, etc).
If the intent of the question is: what would be offensive to others: Stinky, messy foods.
Finally, if you have few small, shareable items (bite size candy bar, a string cheese) to offer to a neighbor you could engender good will and better armrest relations.