I wouldn't change my shoulders. I love my shoulders, they're the most fit part of me (I swim). I wouldn't change my eyes, the shape or the colour. I wouldn't change... my neck, or the shape of my face (much), or the shape of my mouth.
Edit: Oh, and if we're getting into non-physical things, I don't think I would change my personality, or my sense of style. Those are a part of me whatever I look like on the outside.