Civil War II is really standing the test of time. I bought Strategic Command and have been giving it a go. The whole one unit per hex thing is just a turn off. No ability to have generals/admins in the same way that CWII had. I also bought Grand Tactician: The Civil War (1861-1865) last year and just looked at it again. Still seems to have some strange issues, though the devs are certainly working hard on it.
CWII PBEM is really just a true high quality experience. I'd love to see a CWIII. I'm defiantly buying any ACW computer games that come out, but honestly, I just can't get into them the way I could with CWII.