Welcome David. Gus looks cool.
This is a familiar tale, torn between what to do and how much to spend.
The 5D and the 24-105 is a great combo. So is the 7D and the 15-85. The 5DMK3 is a better camera, but you'll probably need either a 500 or a 600mm lens for aviation. Ahh it's a slippery slope.
Here's a suggestion, keep the 5D and the 24-105 as your walk around combo, keep the 100-400. Send the 7D and the 15-85 back and buy a Rebelt4i for your airshow work with the 100-400mm. Done two great bodies all hobbies catered for.