This is why I never book SW when, like the old FedEx ads said, "I absolutly have to be there!"
SW is great if you plans allow you to be flexable. But if you get bumbed, delayed, or canceled, it can turn into a nightmare! Yes, this can happen on the big carriers too, but they DO have agreements with other carriers, and having an assigned seat does lessen (but not illiminate) the odds of being bumped off a flight. I'll pay more for the peace of mind. Plus SW out of Midway doesn't usually beat flights from O'Hare on AA or UA by that much, so for me it's not worth it, anyway. I paid $215 round-trip for travel in December, and I feel it's a fare price for a flight. Could I have gotten $189 on SW? Maybe, but for $26 I'd rather be able to pick my seat and not worry that the flight is over booked by 50 people!