Enotes has a newer feature now which provides much criticism: Contemporary Literary Criticism. Under the topic of Macbeth, there are fifteen essays from which to choose. In the Macbeth Group, there are critical commentaries on each act, which also may be helpful to students' understanding of Shakespeare's tragedy.
Among those listed with the Contemporary Literary Criticism, there is a rather interesting essay on dreams in Macbeth by Simon O. Lesser which offers perspective on Lady Macbeth's haunting dream as well as Macbeth's "what if...?" dreams, or speculations. In a sense, the dreams of the Macbeths are part of the preternatural motif of the play; therefore, essays relative to this aspect may indeed be helpful to students.
For your convenience, links are provided below so that you may examine some of the essays for yourself. Hope this helps!
Thank you. I have signed up for the website but I am still unable to access the entire essay. Why is that?