Eating on the plane

I'm going to be flying Southwest Airlines. On a flight that'll be between 3 1/2 to 4 hours in length.

If you were in MY situation, would you bring some food with you?

I'm leaving early in the morning. I'll be arriving around lunchtime. I have a feeling that I'll get cranky if I don't eat. If you did bring something and ate it on the plane, did the other passengers look at you? Did you get any weird looks?

What should I bring? Trail mix? Breakfast bars? PB&J sandwich? Chips?

Any suggestions would be great. Especially from those of you who HAVE taken a long flight on Southwest.