I like
Mary pretty well. It's definitey vintage once again, so it has some charm. I think I'd like it in the front, because
Marie in the middle is still so commonplace, so
Mary in front is more unexpected. I also don't mind a really nice double Mary-name.
I'd probably use
Polly or
Marion as nicknames, probably
Polly
Of your combos, I quite like
Mary CordeliaMary FleurMary Georgette - Cuuute
Mary Georgine - CUUUTE
Mary Clementine
My fave
Mary combo is still
Mary Celeste as a double name :)