I actually picked up one of those Daybags from the Filson Outlet in Marysville, WA before my last trip to Europe in November... I couldn't resist, given the outlet-store markdown + the 35% Off Sale they had. Regardless of whether most would consider it to be a "true filson"; you really can't beat $28 for a U.S. made backpack with a lifetime warranty.
It folds down flat when empty and fits perfectly inside my Pullman between packing cubes. It's great for throwing in a couple jackets, camera, souvenirs, etc. while exploring a new city.
Attempting to repack 13 days of clothes, souvenirs, and wine after driving over 2,000 miles, through 6 countries.
SUCCESS! (@ Malpensa Airport)