I've used the Civ 4 editor, and it's been great. Haven't tried Civ 5 yet though.
Scale is not a problem with Civ4, since you can zoom in and out as much as you need. Here's an example that I quickly put together for one of my character's wiki pages:
http://wiki.battlemaster.org/wiki/Ni%27Tessine_Family/CorwynI suspect the main problem will be intellectual property concerns though! It doesn't seem like we can just use their copyrighted art for terrain, cities, etc...
That might actually be a selling point in Civ 4's favor. There's a *huge* wealth of "mods", includings custom art terrain that amateur artists have made, and who are very likely willing to let us use for free (if we ask nicely). Civ 5 no doubt always has mods by now (I haven't checked though), but I would guess it's not as complete as Civ 4's and not as high quality.
