The Logos catalog contains lots of old biographies and studies of Calvin, but not much in the way of more recent scholarship. Here's a selection of some that would be good to get:
The Theology of John Calvin by Karl Barth (Eerdmans, 1995)
Calvin's Theology and Its Reception: Disputes, Developments, and New Possibilities edited by J. Todd Billings (WJKP, 2012)
John Calvin: A Sixteenth-Century Portrait by William J. Bouwsma (Oxford, 1989) - "A widely cited, controversial reconstruction of Calvin's thought from a psychological framework."
Calvin: A Biography by Bernard Cottret (Eerdmans, 2000)
John Calvin: Christian Humanist and Evangelical Reformer by John W. de Gruchy (Cascade Books, 2013)
The Knowledge of God in Calvin's Theology by Edward A. Dowey, Jr. (Eerdmans, 1994)
Calvin by F. Bruce Gordon (Yale University Press, 2011)
Calvinism: A History by D.G. Hart (Yale University Press, 2013)
Calvin: A Guide for the Perplexed by Paul Helm (Bloomsbury T&T Clark, 2008)
John Calvin's Ideas by Paul Helm (Oxford, 2006)
Calvin at the Centre by Paul Helm (Oxford, 2010)
Calvin & the Calvinists by Paul Helm (Banner of Truth, 1998)
Calvin on the Christian Life: Glorifying and Enjoying God Forever (Theologians on the Christian Life) by Michael Horton (Crossway, 2014)
The Expository Genius of John Calvin by Steven J. Lawson (Reformation Trust Publishing, 2007)
Calvin's Company of Pastors: Pastoral Care and the Emerging Reformed Church, 1536-1609 (Oxford Studies in Historical Theology) by Scott Manetsch (OUP, 2012)
A Life of John Calvin: A Study in the Shaping of Western Culture by Alister E. McGrath (Blackwell Publishers, 1990) - "A standard biography of Calvin."
The Cambridge Companion to John Calvin by Donald K. McKim (Cambridge, 2004)
Calvin and the Reformed Tradition: On the Work of Christ and the Order of Salvation by Richard A. Muller (Baker Academic, 2012)
The Unaccommodated Calvin: Studies in the Foundation of a Theological Tradition by Richard A. Muller (Oxford, 2001)
John Calvin--A Biography by T.H.L. Parker (WJKP, 2007)
Calvin: An Introduction to His Thought by T.H.L. Parker (WJKP, 1995)
Calvin's Preaching by T.H.L. Parker (WJP, 1992)
Calvin's Old Testament Commentaries by T.H.L. Parker (WJKP, 1993) - an excellent introduction to his OT commentaries
Calvin's New Testament Commentaries by T.H.L. Parker (T&T Clark, 1998)
John Calvin and His Passion for the Majesty of God by John Piper (Crossway, 2008)
With Calvin in the Theater of God: The Glory of Christ and Everyday Life edited by John Piper & David Mathis (Crossway, 2010)
The Calvin Handbook by Herman J. Selderhuis (Eerdmans, 2009)
Calvin: Origins and Development of His Religious Thought by François Wendel (Baker Academic, 1995)
John Calvin as Teacher, Pastor, and Theologian: The Shape of His Writings and Thought by Randall C. Zachman (Baker Academic, 2006)
Reformation Sketches: Insights into Luther, Calvin, and the Confessions by W. Robert Godfrey (P & R, 2003)
Lifting up Our Hearts: 150 Selected Prayers from John Calvin edited by Dustin W. Benge (Reformation Heritage Books, 2012)
John Calvin: Steward of God's Covenant: Selected Writings edited by John F. Thornton and Susan B. Varenne; Preface by Marilynne Robinson (Vintage Spiritual Classics, 2006)