My worst was a flight out of Reagan National to Albuquerque. We loaded the plane, taxied out, and got hit by lightning on the tarmac.

They brought the plane back, unloaded us, inspected the plane, got a replacement, got us out 5 or 6 hours late, landed in Denver at 3:00am. obviously missed my connection 5 hours earlier! Next available flight was at 6:00pm. I got a hotel for a while, got some sleep, and got to Albuquerque about 30 hours after first boarding the plane in Washington.

But, at least some of that was sleeping in a bed in an hotel in Denver.....