If you want to put lots of stuff, camera, 2-4 lenses, flash, laptop size up to 17" and more. You could try the Lowepro CompuRover AW.
http://www.lowepro.com/Products/Notebook_Cases/notebook_camera/CompuRover_AW.aspx
Took this for my Japan trip (hand held bag) and it work perfectly. :thumbsup...