Best answer by Mathieu
One of the easiest things you can do that will incur the minimal cost is to unlock your phones and get a prepaid SIM over where you are and use that while you are in the other countries. This way you are not paying the huge roaming fees that would be associated with that.
Using Whats App will charge you data, which will be a lot more than what you would be charged than a roaming text message.
You should look at what you are wanting to do, where you are going to be and see if using available wi-fi networks in your hotels, local coffee shops, or at the train station can suit your needs. If you just want to check-in with your kids while in the foreign countries, get skype and use that when you get to you hotel room.
On the Koodo side, you may want to switch to a seasonal hold on your accounts. It is 15$ per month per phone and basically just keeps your phone active and does not include any airtime at all. Doing this will make you loose any grandfathered plan you may have, so if you have a really good deal or something then you may want to just keep your accounts going like usual.
Let me know if you have any other questions about anything I mentionned.