Interesting comments, Jerry.

A quick web search reveals that Blue Moon (written by Rodgers & Hart) first saw the light of day in 1933, and was recorded by a host of people including Billie Holiday, Sinatra, Dean Martin and Tony Bennett. As such, it's a kind of easy listening standard.

But the Marcels' version was so very different from other versions that many people do indeed associate it with them primarily. So maybe this is an example where a song can have two 'lives' (in this case as an easy listening song and a doo-wop/pop song) and maybe there's a definitive version for each 'life'? (I can't say which of the other versions would be best for me, as I can't remember hearing them, although I must've heard many versions on the radio, etc., over the years.)

Again, though, it's all subjective.