Hey guys, thanks for the feedback.
The model was fun to make but the 2nd floor interior walls and windows got a little tedious toward the end. I do like how the stairs turned out. I wanted to use TINs for the walls but they don't work well for heavily curved walls with thickness. Instead I used follow-me to drive the curved profiles along curved paths and then did some tweaking with the rotate tool.
The model - which the warehouse wouldn't load - is available here at the bottom of the page. I do not plan to render it but would love to see it rendered if someone feels like giving it a shot.
Regarding how to build the walls. I've given that some thought. I think an approach that might work is to build them up layer by layer about 6" a pour using a flexible thick but bendable plastic mold. One of these days I'll put together a SketchUp model of the jig I have in mind.
Fred