I see the worlds as being cities/provinces in the same country. The country being SimNation. Willow Creek and Magnolia Promenade are connected and in the upper southeast (where it snows). Oasis Springs is in the southwest (hottest part of SimNation). NewCrest is located somewhere between Willow Creek and San Myshuno, which is in the northeast. Brindleton Bay is a coastal town in the far Southeast. Windenburg is in the northwest. Forgotten Hollow is a hidden village right outside Windenburg. There is some type of bullet train system that runs throughout SimNation and gets them to different parts within minutes or a few hours. This is possible because it's the Sims, where anything is possible.
As for destination worlds, Granite Falls is in SimNation, and is closest to Willow Creek. Selvadorada is not in SimNation, but South Simerica. It's the only world outside SimNation so far.
