I opted to go with regular old civilian style backpacks in subdued colors for me and my wife. You can't carry as much in one as a military style pack, but my aim wasn't really to create Bug Out Bags, but rather Get Home Bags. My reason for going with a civvie style pack was "camoflage". I figured if someone see's you wearing a military style pack loaded down with goods you are going to look like a much more rewarding target than someone carrying a smaller mass produced and widely available "WalMart style" pack. I also thought you might draw more attention from any LEO's, National Guard, or whatever policing force we may have operating at the time. I may be way off, but that was just simple thinking from a simple man.
Here is the pack I used.
Trailmaker Double Section Backpack | Overstock.com