I switched to a Swiss Gear bag, the $40 Wired Laptop Backpack from Sams Club.

It hold quite a bit more than the generic Dell bag it replaced. It doesn't look out of place at work. Most of the younger guys and even some of the older guys carry something similar now.

Even carried on one shoulder, it's less stressful on my back. It's a heavy bag though. Then pile in all the crap I carry and it's quite a load.