For those of you that choose not to wear a jacket or vest, like myself, please consider:
http://www.basspro.com/Type-IV-Flotation-Cushion/product/44754/
This is a USCG Approved Type IV flotation device. If the boat should overturn, you wrap your arms around the straps and either swim to shore or wait for help. DO NOT use this option if you don't know how to swim.
Technically, a Type IV is meant to be thrown to someone else and does not replace a vest.
But it is much better than having nothing. And it's comfy on your butt