Jason, you mention lakes and teen-age children. As Benson notes, how you intend to use it makes a difference.
In our family while growing up, we never considered 16 foot canoes as useful or desirable. To our style of paddling (camping, lakes, river cruising) the 17 and 18 foot Old Towns were always preferred. My father and I used to discuss this often and we agreed that the lines on a 17 or 18 foot boat are cleaner. They paddle better. Add to that the extra capacity, room and buoyancy, these were what we wanted for tandem paddling and tripping. My current favorite tripping canoe is a 17 1/2 foot Northwoods Canoe Atkinson Traveller. It is about as perfect as a canoe hull can be for someone who likes to truly use their canoes. On large snarly lakes, it is safe and easy to manage. Point it into a rapid fully loaded, it responds well to the paddle. It can be used solo although it is a lot of canoe for a beginner to handle. I also have a 20 foot canoe that we used as a family canoe before our boys were strong enough to manage the bow with either my wife or I. We would take weeklong trips with 4 of us and our gear loaded in it. I do not have fond memories of carries.
All of that said, 16 foot canoes are far more popular now. Many current paddlers have not experienced the benefits of the longer hulls or they focus more on solo paddling. 16 foot canoes are lighter, do not have as much volume or capacity but if you know how to pack, you can get a weeks worth of gear in one. Most of the canoes I currently buy are 16 footers in part because they tend to be a bit lighter and from a collectability perspective, they tend to have better re-sale value.
Benson suggests that you get it out on the water and try. I agree. As a beginner paddler the extra two feet are not a factor. And, also as a beginner (and a reason I prefer the bigger boats) the stern paddler is not up tight against the rails with their stroke. It's a better boat for learning how steer.
