First of all, you know your children far better than we could ever hope to. Secondly, every child is different. And third, you must evaluate your own trip goals and consider whether your children would fit into that picture.
As a general rule of thumb, we would say that most children should be of school age before they go on a canoe trip. We have had people try it with toddlers that were still in diapers. We were scared to death the entire time they were out, and the parents didn’t have a very good time. Beyond the toddler age (which is more of a safety consideration), pre-schoolers generally do not have attention spans that are long enough to avoid getting bored while mom and dad paddle. They also need to be watched ALL THE TIME in camp. We have had a few successful trips with pre-schoolers, but they were only two- or three-nighters, and the children had spent a lot of time camping with mom and dad prior to coming up.
Once a child is in kindergarten, attention spans start to stretch out to a usable length. By paddling along the shoreline when traveling (which is a good safety tip, anyway), they see a constantly changing environment, and don’t get bored. We tell parents with children in the 5- to 11-year-old range, that they are going on the child’s canoe trip. We would plan travel times and difficulty levels around the child. Activities would center on what the child likes to do.
We outfit literally hundreds of Boy Scouts in the 11- to 17-year-old range each summer. When children reach junior high, they have the physical ability and mental stamina to go on an adult’s canoe trip. Sure, we have to temper travel plans to take them into consideration, but for the most part, they can handle it. Upon reaching 15- to 16-years-of-age, they can do more than most adults. Unfortunately, they usually do not have the life experiences needed to always make sound safety judgments. That is why we insist that an adult ALWAYS be present on a canoe trip