Dave mentions his recent poor experience with American Airlines. I've had a number of those tight connections / run through the airport / arrive at gate / flight is closed / yet there is 5 or 10 minutes until departure time experiences.
However, I can recall two positive AA experiences:
I arrived at my middle seat (9E) for a redeye West Coast to Chicago flight only to find that my left seatmate (9D) was very, very big and had the armrest up while occupying some a portion of my seat. The woman to my right in 9F had a cat under her legs....
I wrote a letter to AA's CEO (Bob Crandall) and they promptly sent me my money back.