Originally Posted by Cyclaholic

I have the same issue and the best solution for me has been to alternate between my big mess bag when I need the volume and a backpack with a padded internal pocket for my laptop. Works for me.

My messenger bag is pretty big, I made it myself (my first sewing project).
1000 Denier weave, waterproof liner, side pockets with key loop, wide velcro closure, closed cell padding in the shoulder strap with quick release buckle and completely detachable stabilizer strap... all the good stuff. It cost me all of about $40 to put together.

Yes, I'm bragging shamelessly now