I divide the worlds into different areas:
European inspired worlds: Henford-on-Bagley, Britechester, Glimmerbrook (because of the Art Nouveau/Arts & Crafts style), Forgotten Hollow, Windenburg, Tartosa.
American inspired worlds, east coast: Brindleton Bay, Willow Creek, Magnolia Promenade, Newcrest.
American inspired worlds, west coast: Oasis Springs, StrangerVille, Del Sol Valley, San Myshuno, Evergreen Harbor, Moonwood Mill, Granite Falls.
Overseas: Sulani, Mt. Komorebi, Selvadorada.
It's own thing: Sixam, Batuu.
My sims can freely move inside their area, but need to take a vacation to visit other areas. :)