I use the Evernote app. I can save reservations, train schedules, emails, pdf docs, word docs, etc. I often copy interesting posts from RS help line, or other web pages into a word document and save in my "Trip Name" folder on my computer. Then a month or two before the trip I start reviewing and save the documents I want to refer to on the trip to Evernote. As I make reservations, I save emails to Evernote. I can tag each note with "hotel", "city name", "things to do" "trains", etc. so I can go to the tag and quickly find what I'm looking for. So if I have a car rental reservation in Edinburgh, I could select either the Edinburgh Tag or Reservation tag and find the car rental reservation. If I have screen prints of train schedules from Edinburgh to London, I'd tag under "trains" and "Edinburgh. It's $5.00 a month and syncs from my computer (that I leave home) to my ipod (our primary computer while overseas).
I still take a flexible 3 ring binder with printouts of only reservations, but any notes, itinerary, restaurants, things to do, are only on my ever note app. For Planning purposes, I use an excel version of a calendar to start planning the itinerary. On the calendar I note, City, hotel, tours, air/train departure/arrival times, travel time from point A to point B, etc,