I recently picked up the LowePro Pro Trekker™ 400 AW for my Rockies trip. The only downside is that it can't fit a 15" laptop as specified. A 14" or smaller should fit. This is a new model, and comes in a 300, 400 or 600 version. This refers to the maximum telephoto lens each bag can carry. Lots of cool features like the waterproof Camelback water bladder pouch. Since Greg Lowe made hiking packs before switching to photo ones, they are head and shoulders above the competition for hiking. I had to buy it when a LowePro rep let me test drive them @ HCE. I hiked up to 15 miles @ 6,000- 12,000 feet in the Tetons with it, and was very comfortable. I was carrying a body, 70-200VR or 300mm F4 AF-S, 17-55DX, Tokina 11-16mm F2.8, teleconverters, 2 liters of H2O, food, clothes, etc. Sometimes I carried my Gitzo 3530 LSV as well, but found that combo a bit heavy for serious hiking at altitude. I should get a lighter one for that purpose. Most of your non-photo gear goes in the top pouch which can be detached for use as a fanny pack with the belt. The built-in rain cover is priceless. As a caveat, I must confess to being a LowePro bag junkie. I've got 4 of them now. :-)
Lowepro | Pro Trekker AW Series Lowepro - Pro Trekker 400 AW Amazon.com: Lowepro Pro Trekker 400 AW Camera Backpack (Mica/Black): Camera…
Video demo here. Start watching @ 3:22 for the Pro Trekker.
YouTube - Lowepro camera bags - Pro Trekker and Magnum