Depends if it's acoustic guitars backing up a rhythm section or if it's solo guitar (er, not "solo", I mean on your lonesome)...
If it's the former, then depending on how subtle it will finally be, I'd either use just a 414 pointing at where the neck joins the body if it needs to be a bit fatter in the mix, or just a single pencil condensor like an AKG C 451B near the nut pointing at the frets - totally zingy sound, virtually no thickness.
If the latter or if there's not a lot going on in the mix then my usual set up is SE Electronics Gemini about a foot back pointing towards the neck/body join, 414 on the frets near the nut, and a sennheiser e901 behind the guitar, quite close to the body, below the players strumming/picking elbow.