http://www.sfbags.com/products/sleevecases/sleevecases.htm
I bought a bag there to try them out, got the Cozmos one. It was so good that I tried out this sleevecase for my Macbook. I'd recommend for what you mentioned to get the sleevecase with the piggyback. I've had it for over 2 years now, and this bag looks as new as the day I bought it. To get an idea on the durability, I took the Cozmos bag with my laptop and a bunch of other items in it to Europe twice (same material as the sleevecase). It's been dragged, dropped, snowed, rained, muddied. The threads don't wear, it still looks very new after I water it down and clean it off. I can't break the zipper for the life of me, and I've overstuffed it beyond capacity many times. The quality is very solid. I know there's a lot of other bags out there, but I've gone through about 15-20 different bags and this one really made a good impression on me.
Regarding the sleevecase though, it fits exactly to your laptop. I added the flap, shoulderstrap and piggyback to it. Makes a very good carrying case. The shoulderstrap has suspension straps in it, really makes a difference on your shoulder. They don't really explain enough on the site about the piggyback, but the piggyback can hold quite a bit. Mine holds my charger, extension cord, mouse, a few random cables like firewire, usb, ipod cables, earphones in earphone case, pens, and glasses case very well.
Anyways, that's my experience with that bag. Sounds like it fits exactly with what you need and no more. Yes, the price is 100% worth it.
