I believe this has been discussed before, but I think it is still a worthy suggestion:
Wish: When a base gets captured, keep all the ack (both town and field) down for another 10-15 minutes.
Why? I see this as having many positives: 1) it extends fights at bases being captured 2) it is more realistic 3) it could encourage more defenders from adjacent bases and 4) it would make GV play in defense of airfields more fun and useful.
As it is, when a field is captured and all the ack magically pops, the fight is essentially over. Any GVs on the field are usually killed by their "own" guns. Defending aircraft are often killed by their “own” ack when this happens. Meanwhile, the attacking force suddenly has the cover of guns they killed only minutes before which they can use to land safely. Usually this means the attackers quickly disappear into the tower and move on to the next target elsewhere on the map. (The common “whack a mole” game-play complaint).
Instead, if the ack were to stay down at the town and field for a short time, the fight would be extended. Fighters already in the air would need to conclude their fights, instead of the ack being the deciding factor.
As it is now, upping from an adjacent field to defend also tends to be a complete waste of time, as you arrive after the field is captured and the "fight is over". But with field and town ack down for a short while, the battle wouldn’t necessarily be over. Newly captured bases would need to be guarded against a quick recapture. Even the largest horde of attackers would need some consideration of defense, or risk losing their gains quickly. Some attackers might need to stay airborne or re-up to defend the field, instead of just disappearing into the tower. Even the “late arrival” who upped from an adjacent field could still be in a position to be useful at a newly captured field (both on the attacking AND defending side).
Having the ack not “insta switch” would also eliminate the very gamey situation where your own ack suddenly starts shooting you. I think there are few things more annoying than launching to defend your field and being shot down by your own ack. This is especially annoying in a GV. As it is, defending a field in a GV is pointless, unless you can get to the maproom. A GV that is not near the maproom can essentially be ignored by the attackers as it can't stop the capture. However, if the “insta magic ack” didn’t pop, even a single wirble sitting on a captured field could keep the field in contention for a short time. This could make defending fields in GV’s much more fun and viable.
I realize this could result in some M3/C47 races to recapture fields, but even in that scenario, all you have is a prolonged battle over a single field, which is far more interesting than the “smash and grab” attack vs. “whack a mole” defense where little real fighting goes on in contention for the fields themselves.