We've used inflatible life jackets for the last decade (sounds great, doesn't it?) They're the only way to go. I will say that we've never needed them, but then that would be true for the normal kind. They're also great for the inflatable boat.
Bought them from Defender, during the spring sale. Got the automatic kind, cheaply. After we sold the sailboat, we got some without the tether. West marine is expensive, and you have to buy their brand.
You do have to wear them when the CG stops you to have them count. Since we usually carry 4 normal kind for guests, kids, strays, etc., that's not a problem.
We tried life jacket jackets in the kayak, and they were too hot.
Boris