you know what would be a cool way to start a new setting? where there is no one central point, no focal point. No Sigil, no Waterdeep, no Greyhawk City... or at least, if you have those, no one of them is more important than the other. each one would have an equal likelihood to be the most important place in the campaign.
in fact, make a totally modular campaign world. yeah, that's the ticket. describe a number of countries, cities, etc... but NO ATLAS. yeah, the DM places whichever lands he wants wherever he wants, and decides how each one interacts with the others based on location and other factors. then you can port in Cormyr, Karameikos, and the Suel Empire, plus another country you made up for a homebrew world, and maybe the city of Dis in the middle of them and they would all fit seamlessly. yeah...
it would be a world where truly anything from D&D would fit. it would be marvelous... *heads back into a fevered dreamlike state...*