Probably the Most Important Items
1. The cloud is here
I highly recommend that you scan everything into the cloud on the internet using a free program like Google Docs or Drop Box. Place copies of your passport, medical records, travel itenerary including tickets and reservations, and contact information. That way, if you lose everything, then you can go to any computer with an internet connection and print out new copies.
2. Paper Copies
Make paper copies of everything. Keep your original passport in the hotel room and take the paper copy with you when you are out and about. Alternatively, tablets enable you to keep electronic copies now.
Go to your states Department of Motor Vehicles or Licensing and get child I.D. cards made for your children. Have your children carry them on them at all times. I recommend as young as two. This way, if they get separated from you, then they have something to give to a police person or other official. Kids easily get upset when lost and do not always think clearly. Train them to give the I.D. to someone who can help.