Here is my working bibliography for my Romans Summer Bible Study.
Craig Keener, Romans (New Covenant Commentary Series)
Grant Osbourne, Romans Verse by Verse
Ben Witherington, Paul's Letter to the Romans: A Socio-Rhetorical Commentary
N. T. Wright, Paul for Everyone: Romans Part 1
Wright, Paul for Everyone: Romans Part 2
Wright, Paul and the Faithfulness of God
I use the NIV Cultural Backgrounds Study Bible.