When planning an international trip with three small children... we found out a few tips and tricks along the way that might be helpful for others.
1) Save money on airfare:
When booking airfare online, if you select to book a rental car at the same time, you save money on the overall booking. You do not need to use the car rental. On our trip we saved ~$300 per person doing this for a total of ~$1500 on the overall booking.
2) Save money on secondary hotel rooms:
I didn't find this out until after we booked all of our rooms, but when traveling with small children that put your room capacity over the restrictions that require you to book a second room, you can tell the hotel your situation and often they will allow you to book the second room for a discount (even up to half off).
3) Passport, Visas AND birth certificates:
I read an article before we left on our trip that due to the increase in human trafficking, many countries are requiring a certified copy of your children's birth certificate in addition to Passports and Visas (when applicable). You will want to look up your country of travel to be aware and prepared.
4) Carry-on bag, just in case:
We brought a carry-on bag, just in case, and boy were we thankful we did! In the bag, we included 1 set of clothes for each person traveling which we used when, 1) we missed a connecting flight and could not get all of our luggage from the airport, and, 2) when one of the boys got car sick on the way to the airport and we needed to change his clothes in the car before he would walk into the airport.
5) Organize your travel documents:
Organize your travel itinerary, tickets, travel contact information in a document easy to reference throughout your entire trip. I had copies of our passports just in case. I used this template to fill in the travel information and sent to a family contact and the person coming to our house to watch our animals, mail, etc. and that I carried with me at all times. I referenced this document almost every day. I also found that it was good to have one envelope with all travel documents and a separate envelope for tickets to keep things separate.