Jim, no singer sings every song in the same key (I have songs that I do in, A, Bb, C, D, E, F, and G ). The range of the vocalist's voice in conjunction with the melody range of the song is what determines the correct key. That might sound rather complicated but what I do is a 'trial and error' method; try it in one key and, if the singer is not comfortable with it, try higher or lower until you find what suits them.
P.S. Scott I was shocked to hear of Bee Rad's sudden passing (I met him at Chordiestock 3 and he was a Member here but never posted). I have say that I have never seen so many wonderful comments about anyone after they have gone as I have about him on Facebook this week. I wish I had known him better.