Co. Aytch by Sam Watkins is very interesting. Somebody ought to make a movie of Sam's story. Kind of a Southern "Red Badge of Courage" only better, IMO.
The Stars in Their Courses by Shelby. Get the audio tape, Foote reads it himself. With his voice and accent, you could almost think Foote was on Gen. Lee's staff and made the recording just after Gettysburg. Awsome.
Stick to the major historical authors for well written histories of specific battles.
Although many books have been written looking at the same battle, different authors will have different styles and explain certain aspects better than another author.
If preservation is important to you, it's the most rewarding activity you can do.