It seems to me that part of the challenge here is to find a monologue where the greatest amount of emotional display can be present to highlight your skill at acting. There are many passages from which to choose. When Juliet learns of her cousin Tybalt's death at the hands of Romeo, there is a great deal of emotional contrast in the passage in Act 3, scene 2. This might be a passage to take because in order to pull it off, there has to be a great deal of emotional complexity. There is grief, mixed with anger, and underscored by total confusion. To display an emotional range, this passage might be one to consider. If one wanted to select a passage of unending grief and a sense of despondency to be displayed, Friar Laurence's unenviable task of explaining everything to everyone at the end of the play might be another option. It seems to me that the actor here has to possess an almost unending reservoir of pain and hurt as the story of both lovers, now dead, is retold.