*Note: These scales are expected for a map where your villager's scale is 1. However, you can just use these scales to adjust for your map
Real-Life Scaling: 7
If you really need to see how big it's supposed to be like in real-life, you are seriously gonna need a lot of space. 4 seems to be fine, but 5 - 7 is just about perfect
That Real-Time Strategy kind of scaling: 1.5 - 1.7
You know those real-time strategy things, build a base and train troops kinda thing? They kinda have those buildings scaled to be small enough to take up less space, but big enough so they seem to be in proportion with the units
The scale I used for my map: 1.9
So if you take a look at the screenie attached, you'll see how I used it in a map of mine, the whole map was tweaked to make everything seem in proportion. I had the villagers scaled down to around 0.8 to match the buildings. I also made a custom PathTexture to match the building in this scale. You can get it here:
18x18GreeneTech.tga