Depth wise, the tumi slim items come close to what I want (3" deep). They are a little bigger than I had in mind @ 16x12 (If I were customizing, I'd probably be close to 14x10, or slightly smaller.)
See, for example. http://www.tumi.com/product/index.jsp?productId=4209925

But the weight seems overkill. 2lbs 10 ounces. Really? (of course, I could do without all the leather accents, laptop protection, and most of the internal organization...) Not to mention the price.