Well, I finally made a decision on the bag. Just ordered a Tom Bihn Indigo Aeronaut with an absolute strap, large packing cube, and end packing cube. I plan to also get an Eagle Creek Pack-It Folder 15 and see where things go from there.
I was going to get the black or steel colored bag because they looked more professional but then I thought... why would I want to look professional? Isn't that why I went into academics?