Are you thinking you might want to design your own house? Anybody can sit down and draw a rough floor plan. But this book tells you to think in terms of how you use space rather than rooms. That simple piece of advice makes you think differently about what you want in a house and what you need. If you are thinking of building, GET THIS BOOK.
Even if you're going to a contractor or architect, get the book and sit down with your whole family to make plans. You'll find out about personal privacy issues, how your rooms and spaces should flow, how to make your house more efficient not from an energy standpoint, but from a "how I use my house" point of view.
This book retails for $26.95 but you can get it cheaper right here - How to Design and Build Your Own House