Anna Kendrick would be a great choice (even if she has been in every movie musical of the last five years--pun intended!)! I love Amy Adams but Betty is supposed to be 22 years old. It's explicitly stated in the book and then referenced how naive and inexperienced she is repeatedly. I know her character is kind of boring and a bit of an afterthought but she really serves as the idealistic foil to Joe's cynicism. An actress in her early-mid-twenties would be much more effective
