Years ago, as I learned to pack lighter, first my Rick Steves Convertible backpack became too large, so I got an essential carryon, which also became too large. At the time I set out on a crusade to find my perfect bag. In the process, I purchased a number of smaller bags - the RS Appenzell bag and what was then called the Travelwell bag by Goodhope. Both just barely held what a would take to Europe for a trip, but neither had any reserve space, so I was reluctant to use either. I didn't like the Appenzell bag for traveling because it loaded at the top, like a backpack, and the shoulder straps were always dangling out, so it became my gym bag. The Goodhope bag is more like a RS convertible, but smaller. It opens flat, like a book, for easy packing and it has hide-away straps. I've made several shorter trips with a little less stuff using the Goodhope bag and it has worked well for me.
So I was disappointed a few years ago when I could no longer find the Goodhope bag online. Goodhope, it seems, only sells in quantities, not to individuals.
I've discovered that Amazon now sells this bag individually. Here is the link. As I said, I have one, but it's a little too small for me to take to Europe for 2-3 weeks. I would use it for a shorter trip domestically. I'm even wondering if it would qualify as a personal item on United when the go the the basic economy fare (a personal item, only). Two of it's dimensions are slightly larger than the personal item dimensions shown on United's website, but the third one is enough less that it's total volume is less then their personal item and it's flexible.