Dr. Gordan Wenham's Genesis Commentaries are the "standard" commentaries for advanced Genesis study and exegesis.  He has written two: Vol 1 on Genesis 1-15 and Vol 2 on Genesis 16-50.

I have come to appreciate the Word Biblical Commentaries over most other offerings due to their presentation of the original text(s) and analysis of the same.  For the Genesis Commentaries, knowledge of Hebrew is helpful, but not necessary, although it may take some extra effort to follow the analysis.

Wenham's commentary presents the recent state of Genesis research, namely the proponents and critics of the Documentary Hypothesis and its variants.  In terms of understanding the form and structure of the Genesis narrative, Dr. Wenham does an excellent job consolidating scholarly opinion and presenting it so that one can thoughtfully form one's own view.

I refer to this commentary regularly in my own study of Genesis.  For those taking my class, I think you will find if valuable to read it in parallel with the course material.

Incidentally, for those Park Streeters out there, I understand that Dr. Wenham was Gordon Hugenberger's doctoral advisor at Oxford.