You could think of it as flying field ack. I would add a feature to the AI definition where you can define a home point for each so that they will disengage and rtb beyond a certain distance. That would keep them from wandering all over the map. Keep them as local defense tied to their home field.
I also think occasional AI bomber streams would be a good feature. Everyone always had fun with the AI bombers in Nef's Fortress Europe. You can't really tell a human bomber from an AI bomber when you are just flying in formation. It also provides focal point for action. Enemy come up to knock them down, friendlies up to try protect them. It suddenly gives everyone an excuse to show up in the same place at the same time and who knows were it goes from there. It becomes a rolling dogfight all the way to the target. Everyone knows where the action is going to be.
...Or alternately, people watch them fly over and don't want to climb for that long, and it winds up with the entire arena getting used to just having strats down most of the time.

Not sure what AI would bring to the MA. The morning crew would likely have some kind of medical event over AI base defenders. Part of me would kind of like to see it. Depending how it was limited, I wonder how easy it would be to cheese.
I personally have never thought ENY does much beneficial. People logging because of it is not good for the game, we need every player we can get. There is little material difference between getting ganged by 10 eny 15 planes with alt for example and getting ganged by 10 eny 5 planes with alt. They're all still faster, and you still can't turn into them without getting in over your head. The only thing different is the defender can run. So up to defend, get overwhelmed, have a chance to run away maybe with ENY. Not seeing much gameplay there.
As for the dar, it's taking some getting used to. I've always thought a heat map like Trips suggested a bit up thread would be a good representation. I'm having trouble untraining my brain to not look directly at the spot on the map showing a bandit. That might get better with time but at the moment I still find it jarring.
Wiley.