Po Campo is a small Chicago-based company that has been making a variety of bicycle-compatible women's handbags since 2009. This year they introduced a larger, briefcase-like pannier to their lineup and I acquired one in trade a couple of months ago. The Loop Pannier is available in several floral patterns, but I opted for the more subdued waxed canvas version. It is umber with tan straps, metal buckles, and honey leather trim. At 14"x10"x3.5" the size is small enough so that there is no heel strike on bikes with short chainstays, but large enough so as to fit some laptops. These bags are designed to be used on the bike as panniers, off the bike as shoulder bags, and as luggage attachments while traveling.
Pilen rack - but the Po Campo straps have plenty of room to spare.
All things considered, I only have one critical suggestion for Po Campo: Think about making a version for men. When I ordered the waxed canvas finish, I was hoping that the Co-Habitant could use it too. He was delighted that the bag fit the unusually fat tubing of his Pashley Roadster rack (no other quick-release pannier we've tried will fit it), but he thinks its shape is too feminine. While Po Campo designs their products with women in mind, I think the versatile attachment system and the elegant briefcase construction of this pannier is too good not to share with the menfolk.