Brent, Sarge, these look fantastic.
Brent, i too like the "finer" texture better also. I think the Solid styrofoam buildings are gonna be amazing.
I started a building with foamcore. I am including a bit of a how-to so the construction is uniform.
What i am doing is taking a wall ( pre-cut to the size i want)
Then I am taking a NOTCH out of the corners. The notch should be as wide as the foamcore you are using. ( 1/4" in this case)
Here is the wall sliced at the edge.

Then the notch is cut out, leaving the cardboard that covers the foam.

Then this piece is glued to the next wall which is NOT cut or notched.

When glued together, they make a pretty tight seam.

You can see you only have to notch 2 of the 4 walls. The other two walls fit right in place.
Remember to cut windows and doors first, before glueing in place.

Adi is just there for scale.

The notches cut out can be used for details.