Drop-D can be accomplished easily, by capoing only the first five strings, at the second fret and leaving the 6th string open. Of course, you're really playing in Drop-E, but it eliminates having to retune, and it fits my voice better. I do this for the couple of songs I know in Drop-D, "Green Green Rocky Road", and "Death Come Creeping".

I learned Mississippi John Hurt's "Payday", in open D (D-A-D-F#-A-D) when I hurt my Left Index finger, last year. I can play "Payday" with only two Left hand fingers, one, if I had to! Capoed at the second fret, Open D becomes open E.

With either of the above tunings, you get a more resonant, open string, alternating bass line, and the melody fingering is easier. I really like the resonance and richness of tone I get with these two "open" tunings. It does help, though, to have two guitars, especially if you are on stage. You should try it and see if it suits you. A lot of blues and most bottleneck blues are played in Open D or Open G. If you have a program, like TablEdit, you can easily transpose between tunings and try things out.