Some good ideas so far. I'm not sure if our idea of fun coincides with HTC's idea of a good map, but I guess I'm more concerned with what the players enjoy anyway.
Throw some strat targets in large numbers near the HQ, and slap a couple of mid alt bases for perk rides and interceptors within reach of said strat. Give the guys who want to up massive HQ/factory raids a choice of targets from a few fields, and give the guys who want to hunt them down and shoot them the same. The bomber/interceptor raids that were run in the AvA were a good bit of fun without being over complex, IMO. An area that encouraged that type of play (maybe it's just me, but I rather enjoy that sort of thing when no one enjoys a tremendous advantage over the other guy) as opposed to 20 forms of NOE lancs belching out 42K #s at every base with some action would seem like more fun for all involved.
I like the idea of smaller fields having limited planesets. I also really liked the concept of a few planes being available at the V bases in the past. Give those areas limited A2G planes, while making it difficult for the divebombing lancs and such to wreak havoc over TT areas.
The center island on one of the maps (was it OZkansas?), when it had early war only, was, for me, great fun, and never seemed to be short of likeminded people.
Anyway, couple of thoughts while I was eating. Who's got some others?