I use a North Face Borealis, an Elecom hardcase (similar to Speck), and a no-name sleeve (nice, but not great).
The North Face is obviously a general purpose bag, but it has lasted through more than 5 years of hauling heavy loads and it has gone around the world a few times with me. That said, I would like to get something durable, but more geared towards urban life. I am still looking for my next backpack.
The hardcase was a great purchase. I would highly recommend it. It appears that they often cause minor abrasion marks, but mine has already saved me from a major gash, and I think it is a great idea for protecting against awful damage like dents or worse. I am glad I got it.
I definitely recommend putting it in a sleeve in your backpack. Rain, dust, leaky pens, liquids, and other disasters occur inside backpacks. Better safe than sorry. Next time I am in the states, I will get the g-form.
http://g-form.com/product/extreme-sleeve-for-laptops/
Watch the videoa and I think you'll be persuaded as well
http://www.youtube.com/watch?v=sdAAbu-nMkY
