I don't recall exactly where I saw it... but there was an environment artist from Epic who detailed how they constructed the architecture modularly in Gears of War. If you want to make environments, modularity is almost always your friend.
Regarding your spec and normal maps: Specularity is never truly just black to white. That's why simply desaturating a color map in Photoshop or Crazybump doesn't always give the best results. My tip is to never use Crazybump for your spec maps, just don't... stick with Photoshop. The first thing I tend to do is mask out parts of the texture map that will have similar specularity levels and apply a hue/saturation to a certain level... but never 100% to complete desaturation. Sometimes you might even want to change the hue a bit too depending on the type of material you're going for. There's alot of trial and error in this, and it takes time to develop an eye for this stuff.
Same principles apply to normal maps. Ideally, we'd all be sculpting every single piece of geometry for normal mapping goodness, but that is not time-efficient for most environment objects. When using the Photoshop NVidia filter or Crazbump, you're usually going to want to "prep" your color map in one way or another. Game-Artist.net has a great tutorial on it: http://www.game-artist.net/forums/su...t-do-them.html
. That tutorial should tell you what you need to know. I look forward to your improvements!