Actually, I'm seeing Heron in general as resembling something like Skyloft in Legend of Zelda: Skyward Sword, but bigger, spread out, and more islands of size, with the main island being a good bit larger than the main Skyloft island.  Certainly you need enough land to farm and raise food for all the citizens.  And instead of birds, we have gliders!

Honestly, I don't think we need a map, at least not more than a general "this area is in this general direction from that one".  We may not need one at all in the sky, just for when we go down below the clouds.  I don't like maps to get too specific unless there's a good reason and a solid plan, because it limits what you can stick in when it's needed.