Sinsull,

The versions that I mentioned are definitely Bluegrass Songs. They may have started as something else, but such is the beauty of Bluegrass. By the time those songs left the mountains they were Bluegrass songs, complete with the high harmonies, Bluegrass Instruments etc.

Is Sitting on Top Of The World Blues or Bluegrass? I've heard it done both ways and I say it is both.

A bluegrass ballad that started life as a Bluegrass song. Several, but give a listen to The Stanley Brothers "The Lonesome River" to start. Carter Stanley wrote it. Carter and Ralph Stanley together were magical.