I'd like to see the following added, as a way to round out the library of vehicles already offered:
(a) P-40E (or any variant, really). It fought in so many battles on so many fronts that its absence is criminal! Sure, it was a dog of an airplane but it could have its uses in a low-alt airfield cap.
(b) M4A2 (or any variant - from an AH perspective they'd play about the same) Sherman tank. Having another tank besides the Panzer would provide the ingrediants for a very good historical re-enactment. D-Day anyone? Iwo Jima? Maybe some Philippines action? Also opens the possibility of doing a desert warfare scenario, too.
(c) SBD Dauntless dive bomber. Battle of Midway, Battle of Coral Sea, Guadalcanal, Rabaul, just to name a few battles where it fought. It managed to sink a battleship and 6 carriers. Isn't that reason enough to include it?
(d) Either the Aichi D3A Val, Nakajima B5N, or Ju-87 Stuka bombers, but only so I can use them as targets.

Their use would mainly be for historical scenarios and I doubt anyone would sign up for a slot in one. Well, maybe the Stuka might attract some attention.
(e) British Matilda (any variant). Rounding out the tank motor pool for a desert campaign, and could double as a Japanese tank for a nice little Guadalcanal or Philippines battle.
(f) a destroyer that could operate independently of a carrier group. Might make for some good high-seas encounters.
Just a few ideas.