My DH and I always bring our own food (he's a pilot, I'm a former flight attendant), so we have some tricks of our own for packing everything from snacks to full meals.
The most common thing we do is to make a submarine-type sandwich. The key to this is to wrap everything separately so you can assemble it on the plane quickly and easily.
Get a nice, long, medium-wide loaf of french bread and slice it down the middle, then cut it up into individual sandwich lengths.
Next, get some plastic wrap and lay out the meats and cheese exactly the length of the bread it will be going on, then wrap it up in the plastic.
If you want to get fancy, get some tomato and slice it up, then wrap in plastic or put in a little container, and some lettuce, and any other vegetable that you like to use. Everything goes into separate containers.
Grab mustard/mayonnaise packets from a condiment bar somewhere (we generally grab them from the airport) and a plastic knife.
When it's time to eat on the plane, all the items are fresh, not smushed, not soggy, and assemble very, very quickly. It's generally best to avoid the vegetables unless you're an advanced airplane sandwich assembler, though
If you want to pick something up somewhere, a caesar salad wrap (or just a wrap in general) is a good bet. Something with flatbread, that's best at room temperature.
Oh, and you SO don't want the boiling water from the plane.
- what's up with the boiled water??????? 
