Stole this phrase from Lyndash in Pam's trip report. I wanted to respond but didn't want to derail the trip report.
Thanks to Mardee, I was inspired to (ultimately) get 5 pieces of Tom Bihn for our Spring Trip. I got two small travel trays, one for each of us, which we used as our individual catchalls for when we arrived and left our accommodations (keys, change, rings, whatever). I bought a cubelet, thinking is was the size of the everyday cubelet. I ended using that for a first aid kit, perfect. And then bought the everyday cubelet which I used as a cross body everyday bag on non travel days (used my backpack on travel days). Finally, I bought my husband the marathon messenger bag for his everyday bag (ulterior motive: it was big enough to carry any of my things that didn't fit in my everyday cubelet i.e. rain jacket and water bottle, which he was very gracious about). These all worked really well for us and I'm happy we got them.