I'd love to have these additional options:

1) Send all Submarines/airships at the same location at the same time (without having to do it manually for each sub/ship)

2) Add a storage for special items where you can store repair kits so the submarines & airships auto repair when needed using those items.

3) Add an option that depending on the amount of items the parts can carry, allows you to pick a "max" timer, meaning your vessels will come back slower but with a full storage.