Wow, never really gave much thought to it b/c the minute I step foot on the plane is 30 seconds too long for me. I once had horrible traffic on departure from JFK-SJU, we taxied the runway for an hour and a half and in the middle, they changed the runway.

Longest upon landing for me had to be LAS from EWR. I think it was an additional 20 minute taxi to the gate.