One or two cities per region worth setting up a temporary home base in, chosen for cheap regional
flights, generous visas on a US passport, livable cost, and a dense ring of 1–4 hour getaways.
Hover any dot for the case for that city.
Primary pick for its region
Strong alternative
Best available, with caveats
Ring ≈ the roughly 2–3 hour flight radius that makes a base work