I'd like to visit the messed up shards, perhaps work to create outposts - some sort of special magitek needed for whatever reason or an item we need to obtain / find.
Mostly vague answer as I dont really think of areas of game as much as scenes I'd like to see but I hope they can slap us again with some grand concept like with ShB's last zone's special area, and maybe hopefully make it last longer. Enjoyed that very much.
Like in FFIX when you go to Terra. Maybe with lots of effort on the ridiculously picture-esq big nature, like big thick billowing clouds wrapping around a sky temple.
I always enjoy the zones where its like the artists and designers got around the table, passed around some really strong kupo nuts, and then went wild (but not wild in the sense of purely chaotic, just 'out there' and 'extra').
Still thinking of Zeal-like area (Chrono Trigger) being a neat thing to see in this game (a bit like Laputa, from Castle in the Sky or Sky from FFXI), so slap some crazy sunsets, massive beautiful cloud walls, wavering grass, high tech yet fantasy inspired civilization.
Also might suggest if our echo gets any stronger we might be able to play through a zone via multiple time lines, you could get some really big differences in an area and tell it's history uniquely. Being a nice way to demonstrate the growth of our strength, even acting as a potential natural gate to areas (getting stronger to expand your search for something), and also opening up some awesome possibilities depending on how extreme you push it. Perhaps with a mix of creation magic and some Cid magitek you're able to take things through as well as gently interact with things (so you can get item drops etc).
Maybe a huge desert with something lush at the center, I always enjoyed that imagery, like Clerya in FFIX. Maybe a rich high fantasy water city tucked away in a sea of sand.
Pretty excited for whatever though so long as they keep up their attitude with ShB, where they were like 'we pushed the system to the very limits for this zone's vertical'. Yeeeeeee! Or obviously as mentioned before, ShB's final area was a wonderful treat. Keep pushing stuff like that, which is probably why I've no real direct comment and think more in terms of imagery. I'm confident whatever done will be done cool.