Absolutely. I stopped flying US Air a few years ago to avoid PHL. I've only flown through ORD three times this year and was cancelled due to weather (or the threat thereof) each time. I've come to the conclusion that the problem isn't necessarily UA or AA, but ORD in general. I started flying NW simply to avoid ORD and PHL. DTW has issues every once in a while as well, but seems to recover a lot more quickly than ORD.