a pattern language
I've been working on an "Old House, New House" website. This has me thinking again about features I like and why I like them. There is a great book called A Pattern Language by Christopher Alexander. I think it was published originally in the late '60's. I read it for the first time about 15 years ago while I was in college. Every few years since, I've tracked down a copy at the library and read it again. The book was part of a larger experiment undertaken by Alexander and his team. They wanted to understand what made some architecture (and city planning) work, and some not.
From this, they distilled a series of rules. Rules like "Six Foot Porch": Apparently, a porch less than 6 feet deep will not be a functional living space. It's not big enough to hold a small table and chairs and allow people to move around comfortably. So the porch is rarely used. Intelligent design calls for a porch at least 6 feet deep.
Of course, the new balcony on our house will be less than 6 feet deep. I tried. But it would overhang the garage in a most inelegant way and call for supports from underneath, which it can't have.
Anyway, I heartily recommend this book if you are interested in design. Sure it's a little dated, but still a compelling read.