In reading the AAR's, I found out a lot about how the various mods affect combat.
Then I clicked on the stickied thread about "links for WITP" (whatever the name is), and looked in the mod section. There are some links to various mods there.
I loaded up the CHS and NikMod.
CHS requires a slightly extended map, and has a more accurate OOB. The NikMod addresses Air to Air combat, and stops some of the silliness in air to air... specifically... if you set, for example, 100 fighters to CAP, all 100 of those fighters will attempt to make an intercept on every strike that comes in. This isn't accurate, as this basically means the planes fly from sunup to sundown with no need to land and refuel and such. Nikmod restricts how much CAP actually files (in addition to the % you can set in the AirGroup orders page), but that, of course, could lead to heavily outnumbered CAP... and given the "stock" A2A engine, numbers really matter in that instance... so the mod also reduces losses your CAP takes (to simulate the fact that bomber escorts don't pursue fleeing fighters 'much').
Basically, in stock WITP, when you decided to take a base (or vice versa), the Air battle for that base would be decided in a couple-three days. With NikMod, that battle can take weeks, which is far more accurate imho than stock. So that's why I went with NikMod on top of CHS.
Also, reading the forum, these two mods seem to have the least amount of detractors.