I've flown in the AvA a couple times. It's not bad, but a large reason I don't spend much time there is not many other people there either. I really do like the idea of flying more historic matchups though.
I know some of these ideas may be kinda "strange", but just bear with me... I'm NOT saying change the AvA wholesale. These are just ideas. Pick and choose as you like or do not. Again, please do not take this as me asking for a million changes.
#1. First server option in the list of servers.
I know this isn't possible, but did anyone stop to think the MA is so full is because it simply is the first item on the list of choices? Think of it like Internet Explorer 3.0 vs. Netscape 3.0. Internet Explorer was included in Windows for free and worked good enough, so who even looked anywhere else? I'd think that just chaning the order to be 1st on the list, while it wouldn't fix the issue, might get a little more "flow" to the arena.
#2. Adjusting Rolling Plane Set (ARPS).
As of right now, the RPS basically states from Day A to Day B, planes A, B, and C are available, X, Y, and Z are available. From B to C, Planes B, C, Y, Z are available and D and W are available at back bases. Instead of doing that, how about keeping A and X as options, or not. Doesn't matter. And enable D and W at ALL bases, but with Perks. The next time period, remove the perks from D and W, and add perks to E and V. This allows you to keep the exclusivity of those limited models, without relegating them to WHERE they can deploy. Meaning these expensive planes can be caught in any manner of fight at any altitude, instead of the higher alts because of the long climb from back bases.
#3. Change the way Radar towers are layed out and active.
This may also be a not possible one, but why is every Radar tower in the center of a field? It wasn't all THAT unusual for a Radar Tower to not be near a base, but instead, closer to the front lines for earlier warning of invasion. Add Radar Towers that are not associated to bases, in "wall" style formations. You could then "pierce" the radar "wall" to do attacks deep into enemy territory without pinpoint notification of where you are, but also there's earlier warning of where an attack will be until those towers are taken down.
#4. Make "Large" airbases capturable, and small/medium ones not. In other words, only like 3-8 Airbases max per side capturable.
This would give a "target" or "goal" for people. A focal point. Combined with the above, it may make it interesting to see a chain of Radar towers go down in a line towards one of the few capturable bases. You can possibly get the "game winners" to play in AvA then, and having that line of radar towers, there'd be more warning as to where they'd strike, since you'd know the direction, and know which one of very few targets they could be going for. More warning = more possibility of setting a counter strike. Counter strikes means more bomber escort needed. More escort = more dogfighting. etc. etc. The fact of there being so few capturable airbases means that if one DOES get captured, it would basically be surrounded by enemy bases, meaning for frantic defense against the surrounding and inevitable attack.
#5. Less Strats. More effect. Put them in towns, like Karelia's cities.
Karelia is freaking gorgeous. But instead of just little factories with no purpose down there. Put the strats behind the airfields, and they can still do fuel, troops, ord, etc. But now that the airfields are slightly farther away, and some airfields can be captured, fuel can be more important. bombs are needed for the pesky radar towers, and troops to get a foothold in one of the limited areas.
Who knows. Maybe some crazy ideas. But that's all they are is ideas.