Hi Sami
Quick idea to open up more of the world map to gameplay - what about allowing airlines based in small countries to expand into neighbouring small countries - maybe by creating geographically or politcially related groups of small countries eg formr British east african colonies, former french carribean colonies, baltic states etc. That way you get a more of the map in play. Airlines like East African did that for many years (up to the 1970s I think).
Just an idea
Mike Swaledale