I use a middle of the road Swiss Army Knife brand backpack, it has a sleeve I put the company laptop in, a 17", and I put the 15.4" laptop next to it in the back. There is still more than enough room for my USB hard disk, two chargers, 4 paper backs, 4 medium hard back books, a car GPS, 5 pounds of change, 2 mp3 players, two headsets, usb charger cables all around, a mp3 to aux input cable, a plug expander and assorted pens, note pads, reading glass in a case, etc. Oh, and the most important thing, there is still room for my herniated disk and all the advil I need to not feel it. Plus it it slings over my shoulders to keep my hands free to deal with stuff.
Silver member by constant and unflinching longevity.