I did have one moment of startling genius however.
We had decided that the bookshelves would go on the mezzanine, and I've been trying to work out the best use of the space up there. It's a balcony that runs the length of the house and it's probably about 7 or 8 foot wide at it's widest point. Our walk-in wardrobe takes a cube shaped bite of that floor space (the loft is basically the top of the wardrobe cube) and that left a little strip that I just couldn't see a use for. It's dark and it's narrow, so putting a book case there wouldn't work and it would be really claustrophobic to sit there. Then it occurred to me that it was slightly wider than the bookcases I was putting up there, and I could line one of those up with the wall, leaving a slightly concealed storage area behind it.
Today I put sliders on the bottom of one of the bookcases, so even when it's full you can quite easily slide it out and get to the nook behind it. Then I took all of our empty suitcases and boxes and stacked them back there. It all fits perfectly! Very satisfying.