Hardcopies And The Cloud. Yes, You Need Both
Likely, you will have your ID, passport and credit cards with you while on the road. It makes sense to have them all in the same place when you travel, but imagine the pain of losing them.
A little parachute, scanning all those documents and plastics, stores a copy in a cloud solution of your choice. This way, you can still access the documents over your phone or via every computer with an Internet connection.
While Apple's Passbook is a great invention, too often, you'll run out of battery at the airport (those Thursday nights before heading home from the client) or there is no mobile Internet available for whatever reason.
To avoid delaying your (probably tight) schedule any further, always have a printout of your itinerary, boarding pass, hotel reservations and the likes with you. Yes, it will cost you a couple of minutes to print them, but you will understand the importance once you missed the last plane home due to an empty smartphone battery.
It also makes sense to bring along a printed list with contact details of the people with whom you will engage throughout the duration of your trip.
A printed list you say? Yes, there will be a time when you lose or break your phone and do not know a single phone number from the top of your head (besides your parents').