I can think of one other (non-randomized) single player video game map that's larger. Daggerfall's.

Anyways, I think it's great that we're finally going back to huge maps and tons of areas to explore. Don't get me wrong, I LOVE FFXIII, but the corridor does get stale after a while, and being able to go off the beaten path and find new things is always a welcome addition to the Final Fantasy games.