Gee, I missed this thread the first two times around. I guess my major experience with a cappella singing is with camp songs and
Gregorian chant (and a bit with sea chanteys, but I have no expertise there).

Yeah, sometimes there are guitars at campfires, but I don't really think they fit. Camp songs generally seem to work best unacompanied.

I prefer singing Gregorian chant a cappella, but I've sometimes done it with organ accompaniment, and it can be good - but it's best with a quiet organ using only one or two ranks. A loud organ just doesn't work with chant. We did a chant Sanctus and Agnus Dei for Christmas Eve with a piano accompaniment, and my opinion was that it was a travesty. I did not put myself in good stead with the choir director for expressing my opinion, despite the fact that I was singing chant before she was born. My opinion is that chant should be light and airy, like lace or a snowfall, but people who didn't grow up with chant tend to make it heavy and dirgelike. Oh, and Rita, chant is one kind of singing that sounds better without ornamentation, I think. Ornamented chant is pretentious.

I guess I do most of my singing a cappella, since I'm guitar-challenged. It works quite well for me, although it's always nice to have a great guitarist like DADGBE to sing with. Sometimes it's annoying when a guitarist give me an uninvited accompaniment - it certainly limits what I can do with a song sometimes. It really bugs me when a guitarist starts playing when I'm leading a sea chantey or a round.

-Joe-