This is one I'm working on now. It's an extremely large island, about twice the size of Texas, or five times the size of Great Britain. So far I've only done the physical geography. I haven't worked out the cities and such yet, although it's pretty obvious where the capital city will go.
I don't have a story yet, but it will be SF, probably a lost colony. I think the colonists decided to settle on this island to minimize their impact on the native ecology.
Yes, as a matter of fact, I
have spent entirely too much time playing with this map. Your point is?