You might also consider an inflatable PFD. The advantage here is a lack of bulk—they fit much more like fishing vests than a traditional PFDs. Some models are “automatic," meaning they’ll inflate when exposed to water. Of course, for multiple-portage trips when you're in and out of the water voluntarily, that may not be a good thing. In that case, a model with a ripcord-like inflation initiator would work nicely. A good example is Mustang Survival's Deluxe Inflatable PFD ($210), which feels more like a rolled-up towel across your shoulders than a life jacket. True, you need to be confident that you'll be in a position to pull the cord when you need to, but when canoeing, chances are you’ll be okay.