Motion sickness? First, take Dramamine, Bonine, or other meclizine antihistamines in advance of travel. Second, avoid greasy or spicy foods, as well as strong smells. Third, sit where you can see out the window so there's not a disconnect between what the eye sees and the inner ear feels. Fourth, drink ginger ale instead of alcohol aboard the plane.
As to what I take - usually I have a small bag of peanuts with me. If I know I'll need to eat aboard the plane, I usually go for Subway.