Interesting that this thread should appear now. I've just started singing 900 Miles again - after many years. I love the song and have found audiences do too. I guess my version has evolved some, unwittingly - I have a more blues feel to it then I catch from the midi in the DT and I repeat the last musical line twice with the lyric:

And I hate to hear that lonesome whistle blow That long lonesome train whistling down.

I'm not sure if that's how I learned it or if I perverted it somewhere along the line. I do remember picking it up from a Jerry Silverman book; The Art of the Folk Blues. My guitar teacher had me working from this book when I was 10 or 11 years old - I still sing a few from those days (of course I may well have evolved a few of those ones too).