A few thoughts on the auto-inflate PFDs....
They come in different buoyancy ratings. Unless you are a very small individual, get yourself one with the highest buoyancy rating.
The cheaper ones only have the rip cord to inflate. That doesn't do you much good if you fall and crack your head before you hit the water! Spend the extra $ and get on that has the auto inflate if the vest hits water. The only down side of these is they can accidently be activated if they are dropped in the water.
Also I'd get one that has the window by the CO2 canister so you can see the green bar if it is armed/pressurized or red if the system has somehow lost its pressure. Good to know before you put it on that the vest will work if you fall overboard.
A coworker of mine lost her brother last year to a drowning. Guy was fishing by himself in a lake, somehow fell out of his boat, no PFD, boat kept going, he drowned. I'm always surprised on the rivers and lakes, I'd say 3/4s of adults I see are not wearing a PFD. Kind of like driving around not wearing your seatbelt IMO.