I use the Co-pilot as my Every-day bag. I carry my wonderful Macbook Air 11" in a hardshell, 8.5x11 folder for papers, mini toiletry pouch (small eagle creek zipper bag), another E.C. packing tube (packed with my Anesthesia emergency gear). All of that is in the back, main zipper section
In the front I keep pens and keys wallet on one side, Snacks in the middle "water bottle" section, and a portable speaker for the O.R. as well as a small electronics pouch and wallcharger for the MBA in the other front section.
I'm very happy with the construction, fit and finish.
The fit is a bit tight for the MBA. If the bag were just 1/2" wider the laptop and folder would be easier to get in and out.
I wonder if a judicious amount of wall padding would add a bit of structure and protection to the back section without adding too much bulk.
I'm 6'4" and don't feel like this is a purse at all. It carries like a small briefcase.
I will also use it as a day bag while traveling.
A serious onebagger might make this work for a short trip.
Overall the bag is highly recommended.
I am considering a small-size Cadet as an alternative... but I hear whispers of a slightly larger Co-pilot which would be preferable. The Zephyr might make things "easier" temporarily, but the extra space would get filled, then I'd be lugging around more than I needed.