nmlhats said: "Being John Malkovich (LaChiusa), Moonrise Kingdom (Sondheim), The Grand Budapest Hotel (Lutvak or Guettel), Little Miss Sunshine (or is that already happening? Anyway, Yazbek), Lars and the Real Girl (Tesori), Edward Scissorhands (JRB)....
As for composers...all of these movies probably qualify as "quirky" and I could probably swap around some of the composers I listed. But I did try to match-make. :)"
From your list William Finn has already adapted Little Miss Sunshine (I missed it when it ran at Second Stage a few years ago, but I seem to recall that the critical and audience reaction was rather tepid).
Matthew Bourne adapted Edward Scissorhands into a modern ballet a few years back as well. I thought it was absolutely lovely, though I know not everyone was a fan. He used all of Danny Elfman's themes and motifs, though if I remember correctly another composer expanded on all of them. However I think it reaffirmed how intrinsically important Elfman's score was to that movie, and I don't think a musical version would work without keeping his work.