While it is primarily for battlemaps, I can see using MapForge to create town & village maps and overland/area maps. You could probably make something along these lines.
image017.jpg

I don't really see MapForge being particularly well-suited for city maps and world maps.

MapForge can be used with artwork from your own library (PNGs, for the most part), so using existing collections like CSUAC and the Vintyri art will be nice. Textures can be BMPs or JPGs, too.

It'll run on 64-bit, but I suspect the executable is 32-bit.