Ok ok....sorry. Couldn't resist.
It varies depending on the tune a lot. Yep, I know, it's a cliched thing to say. However, I guess there are some general pannings I use most of the time.
Bass is straight down the middle.
Rhythm guitars doubled and then layered. One set will be about 50%-60% left/right, and the other set really depends.
Lead guitars, sometimes in the middle. Often I'll pan it off centre and then send it to a reverb that's panned equally off centre in the other direction.
Drums...apart from the kick, which is always down the middle, and the snare, which is down the middle most of the time, the rest depends.