I have had the same experience as Lee. Last February when I was looking into making a background there was some CardStock discussion here on OGR.
I ended up with a mix of stock building fronts from http://familygardentrains.com/.../building_fronts.htm
and I bought a bunch of building from Clever Models, but only constructed them as fronts. Clever is continually making better models, which I will probably buy a bunch more soon. I am laminating the printouts on Foam Core.
Using the Card Stock method with Foam Core can really improve the results. I like how Lee is using people in the windows, that even adds more realism.