Personally having done the regional to world route. If your group does alot of globe hopping and you don't keep your world map up to date I found that you'll find that individual regions tend to not fit as they seemed to in regional play. What I mean by that is when you go to fit the regions into the world they end up to closer or farther then previously represented. Or several regions end up being located in the same area. So it is perhaps a good idea to do a rough map of the "KNOWN" world and pencil in the regional maps as you uses them. I recently LOST alot of regional maps to a drive crash so I now I currently have a unified World map and am currently recreating my regions. and plugging them into the larger map jigsaw puzzle like. Seems to keep placement more coherent altleast for me.