When I have to carry a laptop around I have a tote bag, nope I'm not crazy, I've stiched all the protective bit's from a laptop (Or steal me, as they are known round my way) bag & added a zip, That way I have a nice bag on the outside, with functional on the inside.
Skate backpacks are the best as they often come in more interesting patterns & colours & are super hardwearing, I've had the same one for nearly ten years now. I used to use it for carrying a camera, sketch book etc. as well as work clothes & a change of non work clothes & it's had some pretty hairy abuse. It's a carhart one, but it's pretty huge.