As a place I'd like to visit/see, I'd definately say the City of the Ancients- The Temple of the Ancient's running a close second. As for a place to live, I LOVE Cosmo Canyon and Mideel, and Nibelheim has a nice vibe as well. So does Kalm. One thing that really made FFVII what it was- to me- was the well thought out and placed towns and cities throughout the game. They were all very unique, fitting to their environment, and generally just downright cool.

But overall, the City of the Ancients, Cosmo Canyon, and Mideel are my favourites, in that order.