CptnGumble is correct. Ul'dah is the most ergonomically designed city, nearly equadistant between the other two cities.

Limsa has one adventuring class who can get marks from it. Has a two-three story town structure with facilities spaced out and the city exit quite a run. Plus it's far from Gridania.

Gridania requires the most running to get to from Ul'dah (since Ul'dah to Limsa, once you get to the boat, you boat into the city rather than running to the border to run throough more zone. Maps have limited paths one could take. Facilities also spaced out.