Sliced turkey breast and swiss on pumpernickel or baguette with mayo, mustard, etc.,
plus fruit, homemade brownies or cookies... although, the last time, I actually took two slices of homemade devil's food cake with chocolate ganache!
Once I found a good tiny take-out place at one of the airports and bought a huge grilled chicken caesar salad - it was actually good. Don't remember the name of the place, though, and I only saw it in one airport.