On my current set of front rotors, I got 18,000 miles out of the last set of pads. I was told by my mechanic that this was remarkable, and I should only expect 12,000 miles from pads in city driving.
I was disappointed with my front rotors. I have those fancy rotors that have those grooves in them to help with cooling. After 37,000 miles, the grooves are completely gone from the right front rotor. I had noticed some "grinding" from this rotor, and I went to have the pads changed at that time. The grinding was from road grit/dirt. The grooves in the left front rotor are nearly gone, very faint. I would say the original groove depth was 2mm, judging from the lip on the edge of the rotor, where the pad doesn't rub at all.
After reading some of these posts, I'm not as disappointed with my rotors. They will probably last a while longer, say 50,000 miles.
I do try to take it easy on the brakes, coasting as I approach a stop. No need to maintain speed all the way up to the light, and then brake hard.
