My advice as a kayaker:

1. Tether EVERYTHING! That way when you do eventually flip you won't lose your gear.

2. A cheap fishing PFD works, but one designed for paddling is way more comfortable.

3. Seat cushions and adjustable backrests make life much more pleasent.

I keep all my emergency gear in a multi-pocketed fishing vest which I wear over my PFD. If I go ashore I drop the PFD but keep the vest on.

-Blast