Well, being a Delta style player, I carry two guitars with me when I play.

The Martin stayes in G tuning and I can Capo it to the 2nd Fret and play in A. Also can easily tune the 5th string up to an A and play on D modal, which is cool...

Then I tune my reso (steel bodied) to D (Fred McDowell tuning) and then capo up to the 2nd and be in E.

There, that's 5 tunings with very little work, just the agrivation of swappin' guitars which ain't nuthin". I played 5 songs tonight at a joint down in Virginia with my harp player and played one song in each of these tunings and it didn't slow anything down one bit...

Bobert