The “Mischievous Hands” set.

Personally, I don't think the old cities need to be reworked (at least not so drastically; maybe just change a few things). The idea with Upper Nigon is okay, as is the idea with the dwarves (not the dark ones). The Japanese style from Heroes 6 is definitely not needed, unless they are radically redesigned, but leaving them in their almost unchanged form...

Giants are allies of the dwarves.

I mean, giants are supposed to be big, and dungeons are supposed to be narrow in many places. They'll get stuck and die of hunger.