+ Add more ground vehicles so that there's a balanced line of both axis and allied vehicles - add an allied tank and an axis half-track.
+ Make the Panzers and Ostwinds only available at the vehicle fields. This would be a little more realistic (how many airfields, right now, have a couple of M1 Abrams tanks parked on their tarmacs?) and would create a whole new world of strategic planning.
+ Make the mission planner easier to use - the waypoint setups are cumbersome, as are setting up the min/max numbers of planes. It should default to minimum of 1 and unlimited max. The starting field should be the field you're at. Click on an enemy field and that should select it as your target. When the mission is submitted, the host should send a message such as "Mission planned: A27 to A35 with P-51D, Spitfire IX, and C-47"
+ Add a player-controlled destroyer to open up the naval combat. Alternatively, make a submarine with a deck gun and machine guns, even if game limitations dictate that it only runs on the surface. A surfaced sub can be hard to detect with its low profile.
+ Add a French plane such as the DB520 to attract the European contingent. Would also be nice to have a "Fall of the Lowlands" scenario with it.
+ Add the Ki-84 Hayate and a Japanese torpedo bomber to balance out the Japanese planeset.
+ Add the Ju-87 Stuka, with siren sound effect and tank-busting cannons, to counter the gv threat.
+ Use electronic map markers to indicate gv spawn points.