These are all valid methods. I listed two separate ways. One is essentially mesh decals. The other is multi-texturing. Which approach is best depends on a lot of things.
Hey MoP, Actually, it's a straight up decal with a different set of uv's like you said, but no normal map, just a diffuse. KMan actually did the original asset.
Nod logo is backwards :( taking just the polys where the logo will appear and making just that part unique is an easy, non-decal way to add some simple asymmetry.
use a texture where the tiling is not that visible or use a second material and blend it with vertex paint or use some decals to break the repeating pattern or break it with geometry like vines/ivy
the white base looks pretty clean right now. Maybe throw on some decals to add some love. a few scratches here and there. some battle dmg would be nice.
Thanks a lot for the feedback man, I will go fix the building asap and post the wires, after that I will work on the decals I don't want my scene to look sterile.
You could try to make a set of decal textures/materials and then project them on terrain. With a bit of work you can even get some displacement mapping going on in the material ;)