Not wanting to start a new topic, yet add to this one I also have some ideas to share for possible new Zones. As with Isamu's idea of the valley of the end I like that concept of a top and bottom, yet maybe that could be put into effect as like the Kage and Hokage zones or whatever rank you unlock them, they are advanced versions of the already set 10 zones. If per say the Fire Valley was replaced with Valley of the End it could have the pic of the bottom portion and once the character unlocks the next set of zones the Valley of the End can now be the second portion, so to say the top to keep things interesting. As for zones that could use revision or just are very inactive I would suggest replacing: Fire Valley (4), Ice Lands(7), Main Zone(enhance it maybe?), and well Lightning Plains(enhance as well).
Either revisions need to be made or it is just the lack of RPers compared to the zones and availability that causes in-activeness for certain zones.