I think 'moods' (for want of a better word), can be suggesred better via certain open tunings.

When I start wrapping my head around a song, I try it out in a few tunings first, even to the extent of 'inventing' my own variants of tunings, to accomodate the easier positioning of the left hand on the frets. I'll try virtually all avenues, and explore a few of them a bit deeper.

I may well decide that standard tuning is the right one to pick, then again, I am wont to fly in the face of convention, and do it totally different.

I use DAGDAD quite a bit, though I'm not quite sure of the label 'invented Celtic tuning', Both the major and minor variants of that tuning; F and F#, 'dropped' D, and good ole trusty DBGDGD. The latter one I have violated aon a few occasions, tuning the bass D down to B, or the treble G up to D, or down to B.

I think open tunings should only be a guideline; they are extremly versatile in their 'standardised' form, but they can be 'tweaked' to provide something closer to what you had in mind.

I saw Pete Townsend and John Williams (the Classical guitarist), do an acoustic version of The Pinball Wizard. Townsend played it in open G.

B.