My Air units currently consists of:
4 Geonosian Fighters.
4 Vulture Droids.
3 Droid Tri-fighters.
Two of the Vulture Droids I have customized so they can transform on the fly, unlike the originals where you have to take off the wings and the head.
I came up with this idea before LEGO redesigned their vultures, so its really my own design.