In every single book about ACW you have OOB (order of battle). That would be a great feature IMHO. Month or two ago, somebody posted a pic of OOB and everybody loved it.
Also, I would love to see battles history with forces and generals engaged, with casulties and who won. Perhaps add one more ledger saying history of ACW and then fill that part with fought battles and captured cities. It would also serve as a nice timline so you could check where did you start winning or loseing.
From that ledger we could draw data for generals which is my third suggestion. It sucks a bit as you can't really say how succefull your generals are. Well, you can, but only through seniority points. It would be great if we could click on a general and you would get info on battles he fought and where he lost or won.
Fourth idea would be to add something that Frank Hunter's ACW already has; Alternate history start.
Like following options:
1. Kentucky and or Missouri joined CSA before the war
2. Europe did recoginize CSA from the start
and so on....
For example, with first option we would get stronger CSA and new places for battles such as Indiana, Ohio...
Just my two cents and still enjoying this game so much althought I have it since beta

Forrest said something about killing a Yankee for each of his horses that they shot. In the last days of the war, Forrest had killed 30 of the enemy and had 30 horses shot from under him. In a brief but savage conflict, a Yankee soldier "saw glory for himself" with an opportunity to kill the famous Confederate General... Forrest killed the fellow. Making 31 Yankees personally killed, and 30 horses lost...
He remarked, "I ended the war a horse ahead."