Excellent choices, although Catton can drag if you're not into the details. (I am, so not a problem.) And when you tire of reading, rent Gettysburg, which is based upon Killer Angels. The funny part is that the book takes less time to read than the time to watch the movie.
"Gods and Generals" is a good book, but reads too much like a romance novel in parts.
His characterization of Gen. Jackson--complete with scenes showing his "softer" side--seems artificial. Maybe it's just me, I don't know.