First of all,if this has already been mentioned/proposed in another thread, then I apologise. Had a quick look through recent posts and couldn't find anything like this.
My idea for an expansion is basically a coming-together of various mods in one smooth experience.
I would like to see the option to purchase pre-defined plots of land on Kerbin, and beyond, These plots can then be expanded (with cash or contract completions to there) to create other Space Centres/Aerodromes, in the same way as the KSC is now.
These bases also unlock the CommNet for that part of the planet (on higher difficulty).
Contracts are generated that go between them. Examples:-
Fly x units of liquid fuel to the Arctic Base
Fly a Secret Agent from point A to B, but stay below x metres altitude.
Take 2 Kerbals to SW Crater Mun Base, then change them for 2 more, and return them.
I feel that this will give aircraft more of a purpose than waiting for the dual-purpose engines and gunning it skywards, or those 'take a reading' contracts
I've only just started properly learning how to create planes in KSP (after 150 hours), and feel that this is an opportunity to bring in another style of gameplay.
Feel free to expand on this, or tear it apart!