when shopping for a laptop bag, what is your greatest consideration?

I would look for a stylish design and something easy to carry; sturdy straps so it was easy on my back ... I don't think mine would have to hold too much because I'm always carrying another bag that could hold the mouse and wires and whatnot. I need to get my own laptop case for fall and I think I might get it from dell.com because they seem to have some nice, decently priced bags there.

i think i would look for something that looks cool but can handle being knocked around. also, it would need to have a long strap and a lot of pockets, so i am not fumbling around for stuff. even a small pocket on the strap would be cool for a bus pass etc.