I am looking for a pannier to carry a laptop and other work-related items. While I bike to campus, I often have a fair amount of walking around within and between buildings where is is not practical to move the bike. Are there any panniers that are comfortable to carry around as a shoulder-bag in those circumstances?

Lots of people recommend the Ortlieb and Arkel panniers for the durability and ease of use. I am specifically looking at the Ortlieb Downtown and Office Bag panniers and the Arkel Commuter. However there are several comments about how they are uncomfortable to wear as shoulder bags because the hardware digs against your body. Can anyone comment or recommend a good pannier that would also work as a good shoulder-style office bag?