There are 4 things I would really like to see In AH II:
1. More realistic Bailouts. Also, after you bail out you could make yourself useful and fire your rifle at something.
2. The abililty to change skins. Just like in CFS3, I think you should be able to edit your paint job while playing the game to just make it look cooler or make it match the arena (desert camo, etc.)
3. A better damage model, in which you can actually see bulletholes.
4. I really think you should be able to have more than 1 gunner. You should be able to stuff a bomber with 10 guys, and each gunner would function like a pilot, with the ability to bail out individually. I think it would also be a good idea to make a new "plane" radio channel which contacts everybody currently inside your plane.