You owe it to yourself to check out the Boblbee.
http://www.boblbee.com
They are expensive, unusual, but indestructible. I have two and they are about my favorite inanimate objects of all time.
I've beaten mine on both daily commutes to/from work and on countless business trips around the world - never having damaged a thing inside.
The only problem with them is that they draw a great deal of attention: "What is that?" "Is that some type of sled"? You get used to it after a while.
My current daily rig is a Megopolis Sport with side bags and rear netting. Its laptop compartment holds up to a 15" apple notebook with ease. The 17" sort of fits. I also have a "People's Delite", which is perfect with a 12".
For any laptop uses, I'd suggest the internal electronics organizer. It adds a nice compartment for a power supply, cables, etc.