Thanks for posting. I love drawing backgrounds. I especially like that method of pulling a 2D schematic up into a 3d space. That one will come in handy!
I'd like to add another thing if I could. Programs like sketch-up, Poser and Daz are quick and easy ways to build spaces in 3d that you can use as reference. They're especially useful if your scene is going to be in one place for a lot of panels.
Lastly, drawing out an entire facade in 2D would no doubt work great for maintaining accuracy, but if you're only going to be drawing the building once, that might be a time waster that comic artists can little afford.