When I bought my brand new PowerBook G4 17" in 2004, I splurged and bought a Brenthaven backpack for it. Back then it cost a good deal more than the usual backpack -- around $75 -- but I thought it would be worth it since I lugged around my PowerBook nearly every day and it looked like the Brenthaven provided better padding than the competition.
Since then, the backpack has housed a succession of three 17" PowerBooks and MacBook Pros under very heavy use. The amazing part is that outside of being a bit dusty, it's in just as good shape as the day I bought it. No frayed stitching, no stuck zippers, no torn dividers. There is no sign of wear and/or tear whatsoever. And if there was, or ever will be, all Brenthaven bags come with a lifetime warranty.
The backpack is wonderfully designed for protection, storage, and utility. Being made of ballistic nylon it's nearly indestructible, but the design is what really sells it for me. The main section that holds the computer contains a sleeve, attached to the bag by velcro, that's extremely well padded and can be used outside of the bag if you wish. There are three file dividers, and six pockets to hold most anything. In front of that is another compartment with two large netted pockets, pen holders, and another four more pockets of varying size. Between these compartments is a deep open pocket to let you store and retrieve items quickly.
On the front are three more zippered compartments. One on top is small but quite deep, the second covers the front of the backpack vertically, and the third is on the bottom where you can store power supplies and cables.
All of the pockets and compartments are more capacious than they seem. I've often been surprised at just how much stuff I can fit into the bag.
The backpack is perfectly weighted and quite comfortable to carry for long periods of time which is important to me since my back has seen better days.
The picture in this post is of my bag, which I'm sure is discontinued, but can still be found at Amazon.com. The current line of Brenthaven backpacks are designed a bit differently and can get very expensive, with one as high as US $149.99! But if you are looking to buy one MacBook/Pro backpack for the rest of your life, or want to gift a friend with maybe not the fanciest looking, but by far the finest crafted backpack I've ever used, look no further.