Oh, I so wanted to come in here and just say that "Dragon Scales" are the best. Or go to my bathroom and get the brand of my scale and explain how it's only because it was on sale. Hehe...ok, smart-alek I know.

Pretty much all the maps I've made are 1" = 5", hex or squares. That's just because it works for most miniatures in tabletop games.

I think the scale depends on what the usage will be. If you want a space ship to land on a hex and fill it up then figure out how large the ship is and go from there. If it's just a visual representation of say a planet what's the use of the hexes anyway? If you are going to put a marker down where your adventure party is that might matter, but again, it really depends on what you are trying to display. If the part is in the same hex for a week or so game-time then that's really probably not the map you will be using as you would probably have a more detailed map to work from.

You seem to have hexes within hexes so I think you just need to determine what your smallest hex is and go from there. I'm thinking there hasn't been a lot of response because most probably change the scale to fit the map.