The Recon Backpack (Khaki) from Hex is an excellent alternative to a traditional laptop backpack. This is a slim, lightweight pack that holds a lot of gear including a 15" (38.1 cm) laptop as well as an iPad or eReader. In addition, there's ample storage space for cables, adapters or a mouse.
The pack is made from heavy-duty 16 oz (454 g) washed canvas. A top carry handle makes traveling crowded city streets much easier. There's a measure of added security as well, since the Recon doesn't look like a traditional backpack or laptop case.
This understated pack doesn't require fancy straps or couplings or hours trying to figure out how to use or carry it. Just place your computer and other gear in the zippered accessory pockets and you're ready to hit the road.