[thstone]

Do you ever notice any difference between the right and left side? Any pull to one side? Can you hear the pad dragging on the rotor or can you feel a difference in resistance when rotating the wheels (on lift or jacked up)? I would expect there to be some kind of noticable physical symptom with that much difference in pad wear.

With that being said, it certainly points to the calipers and as Burg suggested, do both at the same time.