Picked these up this last weekend. The Timbuk 2 Tandem Pannier Messenger. I’ve only done one ride with them but I’m pleased. Quick attach to the bike; just as quick to remove. Relatively spacious and the company claims you can carry a 15″ laptop. These are not touring or camping bags, but I could imagine using them for an inn-to-inn overnight. Certainly you could do some light grocery shopping and would be great for school. Made from waterproof, tough tarpaulin material, finished with reflective highlights for night visibility.
The best feature is that this is made saddle bag style. The center piece fits most rear racks and has Velcro straps to secure. There are also small magnets on the inside of both bags. When removed from the rack the bag collapses down for easy carry. Comes with convenient handle and a shoulder strap for carrying.
[disclaimer: purchased this myself, receiving no compensation for my gushing endorsement]