Who are some actors (from this century) who could represent characters from Romeo and Juliet?

Nurse: Melissa McCarthy, because of her comedic timing, physicality, and friendly presence. 

Lady Capulet: Angelica Huston, because of her brooding nature and sometimes cold comments. (For example, see Angelica Huston in The Life Aquatic with Steve Zissou.)

Friar Laurence: Jeffrey Tambor, because of his likeability and history of playing patriarchal figures. 

Benvolio: T.R. Knight, because of his trustworthiness and history of playing the middle man. (For example, see T.R. Knight in Grey's Anatomy.)

Rosaline: Chloe Sevigny, because of her aloof nature, youthfulness, and attractive features. In a way, Rosaline could be anyone since she does not appear onstage in the play.

Peter: Michael Cera, because of his earnestness and frequent tendency to miss the mark and fail to deliver on assignments. (For example, see Michael Cera in Arrested Development.)

Balthasar: Macauley Culkin (as a child), because of his boyish looks. His mischievous nature would match Romeo's, but Culkin would remain helpful and subservient.