The inflatables are comfortable, but can activate when you don't want then to. The less expensive ones use a small 'pill' similar to an Alka Seltzer to activate the inflatetion.
If they get wet in the rain, splash, etc they can activate. there are even cases of them going off just by soaking up the high humidity we have here in south Louisiana. The more expensive ones use a hydrostatic pressure valve that only activates when the vest is submerged and the activation is caused by the sensing of the change in pressure due to the unit being underwater. (they cost about $200)
If you decide to go a traditional vest, get one that's made for fishing and has cutout arms for more movement and mesh panels to keep you more cool and comfortable.
If you're looking for a kayak shop in the New Orleans area, Masseye's has stores in New Orleans and Metairie.
I have used the Onyx Auto/Manual vest from Academy for over a year now. Its been through several of the summer time thuinder storms that were soaking frog chokers. I have even hosed the dried salt spray off of them after getting home and have never had an issue with them. If I remember right they ran some where just under $100.00
Its also like someone else stated in this post that they are very comfortable and after awhile you don't even realize you have it on.
http://www.academy.com/webapp/wcs/stores/servlet/Product_10151_10051_277701_-1?color=Blue&N=581132454
I have 2. One for me. One for 1st passenger. Love it and doesn't break the bank.