Perhaps the handcuff is extreme, but don't leave it or its contents unattended. Use one hand at the urinal (if applicable), saving the other to hold the briefcase. Use stalls with walls on two or more adjacent sides, keep briefcase on side of toilet with wall. Don't leave it on the convenient little shelf by the door in the bathroom (think I've seen a lot of dumb stuff in the bathroom?) Don't leave the stuff on the table as you walk across a huge room get more food/coffee.
Also, insurance for hardware, encryption for data. IOS has full disk encryption and Android might; truecrypt is cheap and easy to use and each major OS has its own native encryption solution.