Watch the Breakdown online guitar lesson by John Stowell from Modern Chord Melody

Haiku Breakdown As with several pieces in this course, I'm playing the melody again on another guitar tuned a major third lower (C to C, same relative pitches as standard tuning). The lower pitch works better on some tunes than others. The open nature and rubato feel of "Haiku" lend themselves well to this tuning.
If you want to experiment with tuning lower, you can also hear and feel a difference with an instrument pitched a whole tone or minor third below concert. Baritone tuning is a fourth below. Pat Metheny has created an interesting sound by combining a bartione and Nashville tuning on one instrument, tuning down a fourth but taking several of the high stings up an octave in that register. Given the availability of good cheap guitars, you might consider buying an instrument that you can use to try some different tunings with. Of course you can try different string gauges as well. Because I have a light touch with my right hand, typical gauges for a jazz set (.012-.052) work fine for me.
On "Haiku" using the lower tuning, I"m aware that the open strings used in the melody are prone to more sustain. In addition to being careful with my right hand to achieve a balanced sound, I'm also occasionally dampening notes.