I just got around to changing my driver'* side wheel hub (planned on doing it last week, then life got in the way). When I pulled off my caliper, I noticed that one brake pad was literally almost metal, while the other one had a good 1/2-3/4" of pad left.

Is my caliper sticking or something? I'm trying to come up with another reason, and nothing is coming to mind.

On the subject of calipers, is there a nice Stage-1 type caliper for W-Bodies? I was looking at GTP calipers, but I need 18" wheels for that. (Mine are only 16")

Almost certainly you have a sticking calliper.
However it'* a simple fix, remove the calliper and free off all moving parts and reassemble after giving them a light coating of copper grease.
Make sure the pistons move freely as well, get a friend to push the brake pedal down and you should see the piston(*) move out, when he releases the pedal it should move back a fraction. If it doesn't then you should replace the seals (kits are available from any good autoparts store), you will get your hands dirty but save $$$ over replacing the calliper.
Do this on both sides and replace ALL the pads. Check the disc (rotor) for one sided wear from only being loaded one side too.

Yep, sticking caliper. You need to clean up the slide area and put a little lube on it.

they have caliper specific grease, dont know what copper grease is personally.

Copper based grease is what we use over here as a lubricant for moving parts in a hot environment such as brakes, it is also used for lug nuts and many applications to prevent nuts and bolts seizing (freezing?).

i use these,

http://www.permatex.com/products/Aut...per_Lube_1.htm

http://www.permatex.com/products/Aut...ubricant_a.htm