I do, and I wish that people still used them instead of the backpacks that have become ubiquitous:
- Briefcases easily fit into overhead bins on aircraft, and they can be stacked to use all the space efficiently. Backpacks waste space in the overheads.
- Backpacks take up too much space on the Tube, whether they are being worn (worst-case) or put on the floor (still inconvenient).
- When people wearing backpacks turn suddenly to one side or the other, they're likely to whack the person standing or seated nearby. I had this happen twice last week.
- Briefcases protect paper documents better than backpacks. Yes, those of us who deal with legal agreements still use paper.
Zippered compartments on backpacks can be helpful, true. But if you are frequently having to reach into backpack pockets for items needed during travel, I heartily recommend a travel vest. You will wonder how you got along without one.
My late Aunt Dell gave me a thin Samsonite briefcase as a gift for high school graduation. It's indestructible and I still use it. In the late 1980s Gail gave me a nice burgundy leather model from Korchmar; I still treasure it and bring it out for special occasions. And on my international business trips, I use a nylon laptop bag similar to this from Eagle Creek. It has held up well throughout about 1500 flights. (Hint: never buy black. Most bags are black. Buying a black bag increases the chance that someone will inadvertently take yours. If you must buy black, put a strip of colored tape on it.)
But no backpack. Those are for camping or school.