Jerry,
I guess most people know me as an unaccompanied singer (The Boarding Party, Rock Creek) but I do play guitar a little, to accompany songs that I think lend themselves to accompaniment. I usually finger pick, using thumb and index finger (and occasionally the middle finger as well) but I also flat pick when the song seems to call for it. I played guitar (1950s Gibson J-50)in a bluegrass band called 'None of the Above' around 1970-72, flat picking mostly. And even earlier, I played backup guitar (1940s Gibson J-35) in a straight-ahead C&W band called 'The Rhoen Valley Boys' in Germany about 1965.   

Like many of the folks who have already written in to this thread, I let the sense of the song, or the overall style, determine what picking or strumming I will use. I agree with you that it is somewhat discouraging to go to a festival workshop where the speed demons have taken over.

Padre