I won't let my son fly Southwest because they serve peanuts. I would be uncomfortable whether they have them on THAT flight or not. I figure it's all over their seats and everywhere. We just choose to fly airlines that don't regularly serve peanuts to minimize risk. Continental, United, American, Alaska... I'm sure there are more. They have some treenuts and some "may contain" snacks, but don't generally serve peanuts. I just browse their website until I find what they serve. Look under "in flight services" or "traveling with disabilities."