3 Guitarists?

^kevin shirley's been doing that on the recent maiden albums. imo it sounds like shit, especially on the live albums, where you'd expect each guitar to have its position unchanged during the song.
on a studio album though, experimentation can be good, but you have to make sure you don't overdo it.
 
My band actually has three guitars so I feel like I have some good input to offer. I am in complete agreement with 006 on this whole issue. Automate the panning as appropriate for the purpose of each part. If at any point it's hard to get all three parts to sit well in the mix, chances are that all three of those parts don't belong together in the first place. And, there's nothing wrong with doubling and hard L/R panning select parts wherever necessary. Afterall, doubling often is supposed to sound as if it's only one guitar, but it's doubled so that it can be perceived as something other than mono or off to one side. Just use your best judgement, and don't spend time worrying about keeping one guy in one sonic position the entire time.
If anyone is interested, you can hear a couple of my band's three-guitar songs that I engineered and mixed last summer at www.purevolume.com/bilateral
You'll probably wonder why I'm on the Andy Sneap forum after you listen to one of the songs (genre-wise), but we've abandoned these past songs and as soon as we have a new vocalist I will be sure to post some of the metal stuff that we've more recently written.