Since I am a relative newbie on the New Testament epistle to the Hebrews, readers may be interested in a blog dedicated to the letter called Polumeros kai Polutropos. The author, Dr. Brian C. Small, has written a monograph entitled The Character of Jesus in the Book of Hebrews. The blog has very helpful bibliographies of books, articles, dissertations, reviews, and devotional material for your perusal.
Also, a review has been posted of Hebrews in Context (ed. Gabriella Gelardini and Harold W. Attridge; Leiden: Brill, 2016) at the website Review of Biblical and Early Christian Studies. The content explores the various contexts of the text (Jewish, Hellenistic, Roman) and brings together many papers presented at the Society of Biblical Literature unit dedicated to Hebrews. Another forthcoming publication that caught my eye is an edited collection of key articles on Hebrews that have been compiled by Scott D. Mackie in The Letter to the Hebrews: Critical Readings (Bloomsbury T & T Clark, 2018). The text that I am considering for my class, since it includes a range of scholarly perspectives and explores both historical and theological approaches to Hebrews that would be suitable for a Seminary audience, is The Epistle to the Hebrews and Christian Theology (ed. R.J. Bauckham, D.R. Driver, T.A. Hart, and N. MacDonald; Grand Rapids: Eerdmans, 2009).