I've started a serious effort at Extraordinary Circumstances: The Seven Days Battles by Brian K. Burton. I say a "serious effort" because I've skimmed the book in the past, or concentrated on a handful of short passages.
I rec'd a nice copy of my own as a Christmas present from my son, so I intend to read through slowly and methodically, paying attention also to the source notes.
This isn't the first book I've read about the Seven Days Battles, but the consensus around here seems to be that Burton's is the most detailed, and probably the best.