Well..... I think that what you noted characterizes most of the good/popular folksongs that populate this forum.... of which there are thousands upon thousands that could be named.... and that if you are looking for material to use, yourself, your best approach will be what I suspect everyone else does and that is to follow your taste and try things to see what works.

I also think there is no such thing as a non-folkie audience. I might have agreed with you, once upon a time, that there is; but my experience has been (both singing and being in audiences) that folkies are everywhere, and that people who might SAY they don't like folk music have not heard it done in a style that reached them-- yet. Because good music is good music, and it transcends expectations.

So-- your version of your songs (the ones you choose) might be JUST the music they'd love to hear.

~Susan