Nice idea t1ck!
I had been thinking about maybe making some of the interiors square - Not sure if I will go for the full inverted concave effect, but I have been trying to think of ways to create more space for toilets, etc, and your idea has set me off thinking of a new approach!
Well, I have been struggling with dodgy internet connection for most of today - must be my turn! I did manage to do a bit of work on my project - I imported my vacuum guy to get a sense of scale and realized that everything was out of wack so I have been resizing the rooms so they all work together.
I have started adding an upper level with a balcony and walkways to each of the roofs and I also began building a bit of a podracer type vehicle to sit out front.