I was an avid, and seriously addicted, ACW I player and am planning on purchasing ACW II as soon as I get my new computer (in fact, it's the main impetus for buying a new computer).
I never got into playing any games via PBEM, so I'm curious if there is any "live" 1v1 multiplayer functionality in ACW II, or if not, will there be? It could be setup such that 1 player initiates the game as the host or administrator, sets the rules / constraints (eg, 5 mins / turn, 1862 through 1864 only / full campaign, etc.), and opens the game up in some kind of "live" game forum accessed through the game itself. This would permit faster, full-length games that could be played in just a few hours. Not as important, but related to that, people could also get ratings (or ranks, hehe) based on the outcomes.
Related to the multiplayer possibility, do you think it would be possible to do cooperative 1&1 vs COM or 2v2 games (eg, one person plays "east" and one person plays "west")? There could also be a chat function or VOIP chat to coordinate things with your ally (and maybe a general chat to for bio breaks or just fun commentary with your opponents)? Maybe big decisions would require a 2/2 vote to jointly enact. Other than that, industry production, recruitment, and most everything else could be done the same but based upon a smaller region. If someone leaves early, the player can have the option of turning the other theater over to the computer or taking it on themselves.
As fun as it was playing against ATHENA, it was never quite like playing another human opponent. Also, I find the prospect of breaking down responsibilities and coordinating with an ally could help speed the game up and add another level of fun.