[drohem]

I would suggest option #3. It works best for me, since I have only created an island continent; about the size of Australia.

I a sure that there are some people who have developed a whole planet with land masses, races, and cultures, but I would venture that most have just focused on one area.

Option #3 would be the more than likely be the best way to integrate everyone's ideas with the least amount of the pigeon-hole effect.