I realize that some have reservations about the inflatable PFD's but if you go in the water unconscious a regular PFD has nothing to possibly keep your head out of the water. The inflatables have a large blown up portion at the back of your head which is supposed to roll you over and keep your head out of the water. They don't guarentee this of course...
That being said any type of PFD you wear, your far and away safer than those who don't, I'm a little too lax on this myself...
If your are considering any type of inflatable, the automatic ones should be considered for sure because if you go in with a manual one unconscious then you have nothing where a regular PFD will at least give you a fighting chance. The auto inflate ones also have a manual back-up.