Lucy Hale is much too young to be in the film, and I think Kristen Stewart would be a bad choice seeing as how the Fifty Shades trilogy is based on the Twilight novels - it would really rub people the wrong way. I'm not sure who Lyndsy Fonseca is but based on her picture, I like her
I'm not sure who I'd like for Ana, but I've got two ideas for who should play christian:
1) Wes Bentley
2) Matt Bomer
Wes is my #1 pick - he's exactly what I imagined Christian to look like (for some reason I can't see Christian as auburn-haired even though that's how he's described in the book
)