Best camera sling / backpack?

Case Logic DCB-308 SLR Camera Sling (Black) is larger and it will fit both my Rebel XT with the 70-300mm lens, and my new Rebel t2i with a 18-200 lens at the same time! In addition, the other large pockets have plenty of room for the manual, battery charger, extra batteries, polarizing filter, etc. I can easily fit a 6 x 9 inch sketchbook in the large flat pocket on the exterior surface. And, for the times I don't want to have to carry a purse as well--I can fit my wallet in this as well!