Yeah I know. The FAQ. Really hoping I won't have to search every corner of Wonderland, Agrabah _and_ Hollow Bastion just to find the best farming spot for these guys. Hoping somebody knows a good spot.
I can't remember a good spot off hand for air soldiers, but Bambi might be a better bet. Fill his gauge 3 times (18 kills) in Neverland for a 30% (75% with 3 Lucky Strikes) chance at one. And every extra charge (6 kills) after for another shot.
Stack MP (and Cheer) for a longer summon, and a stronger Thunder (if that's how you want to clear the room).
Personally, I prefer using Bambi for the likelier chances. My method is: land at the Cabin, head to the bottom (Freezer), head back to the other Cabin (the one with the ladder), summon in the Captain's Cabin, and then alternate between the 2 areas.
So: Freezer -> Galley -> Cabin (w/ ladder) -> Captain's Cabin -> Ladder Cabin -> Galley -> Freezer. This is also, by far, the best source of Spirit Shards as well (the Freezer gives 3 guaranteed Spirit Shards and 2 possible Spirit Gems; the Captain's Cabin gives 2 Shards and maybe 1 Gem.)
But if you'd rather use the Air Soldiers, you can find them all around Wonderland, and in the Castle Gates, Great Crest, & High Tower areas of Hollow Bastion (as well as their adjoining Lift Stops)
Things I learned from Earthbound: Toothbrushes blind people, mushrooms are evil, and trees explode when they die.