Count me in to the folks who would love to see this on stage.
It mainly relies on the fairy tale world, as opposed to animation. They could go from bright, happy, and curved designs for sets and costumes (circular towers and swirls inside things and such), and use dark, solid, stiff design aspects for New York (a lot of straight lines, stone, black and grey, etc.).
As for the ending, I'm not quite sure. Projections? Animatronics (sp)? She could turn into a beastly werewolf or something as well because youngsters would still find that scary.
As for casting, I would love to see Megan Hilty play Giselle and maybe Gavin Creel as the prince?
(Some of this may not make sense, I'm sorry)
Every living soul has got a voice - you've got to give it room and let it sing.