I currently have three diaper bags: the Combi backpack, the Lands' End tote and the Bjorn hard-case. I've never used the Bjorn and am considering returning it and getting a Lands End Do-it-All instead. Anyway, I am wondering which of the 4 would be the best bag for airline travel? Or if not among these four, what else would you suggest? I'm going to San Francisco (from Chicago) for a week in May. It's a 3.5-hour flight and it will be just Nate and me on the flight out there, although my husband will be with us on the flight home. I plan to bring only the diaper bag, the carseat and the Baby Bjorn on board with us, and gatecheck the stroller.