I would suggest the Eagle Creek Convertabrief or Straight Up Business Brief:

http://shop.eaglecreek.com/backpacks/l/412

I have their Conor backpack (similar to the Universal Traveler Backpack) that is just about perfect for me, but think it looks a little more casual than professional, but I'm an engineer, not a lawyer.

The eBags TLS Professional Weekender looks nice. There is a fairly thorough review here:

http://1bag1world.com/2014/09/gear-r...nal-weekender/