One of the concerns I had with my measurements was that the space allotted for the cities didn't have much wiggle room. Literally.
I measured 23mm from one corner to the opposite on the base of a city. So there's a 23mm circle at every corner of every hexagon. But I didn't want 23mm between the hexes. It just looks wrong — too far apart.
So I pulled it all in, making the hexes intersect with the city cirles a little bit. The cities don't need the area of the entire cirle, after all. According to my calculations, it should work, but "according to my calculations" is always what the scientist in the horror movie says before he creates an undead planet-destroying supervirus. I wouldn't know until I brought my paper cutouts home and tested it out.
It worked. Yay.