I'm also most interested in exploration and man, watching that city and map last year was a blast.
I've been dying to see more about the world map, but specially about the cities and towns. It's something I miss so much, exploring the landmarks, entering people's houses and castles, talking with villagers and doing sidequests or just enjoying their conversations and the lore.
Accordo is HUGE, and I'm really intrigued as to how much of it we'll be able to explore, I cannot imagine. About Lucis, I guess the castle (they confirmed it when it was Versus) and some sorroundings (like those streets in the 2011 trailer), but given how massive it is and (supposedly, sure) that it's going to be invaded (and Noctis' gang is on the run), I don't think it'll be very significant, and that's actually alright.
BTW, wasn't there going to be a city based on Manchester? That'd be weird, I don't think it's a very remarkable city (and isn't Lucis the only modern city? maybe they're going with an older Manchester).