One thing that I read online about which I was skeptical but which turned out to be partly true is that it was offered to Rex Harrison, who was intrigued (and later did a Don Quixote TV movie). He was announced in the press as having been asked to do the role, and it was said that he was considering it, but I think some online sources go farther and state that he actually played it somewhere and dropped out because he couldn't sing it and he was replaced by Kiley. That never happened. He never even agreed to do it anywhere. Kiley created the role at Goodspeed and then of course on Broadway.