Magic Marine makes an awesome PFD! It's slim, so it doesn't make you feel like a snowman and it also doesn't ride up. There's a built in pocket in the back for a waterpack and internal routing for the hose/mouthpiece. Additionally, there is a large pocket on the front that will house most any small items/spares you'd want on you (whistle, shackle, flares, food, whatever).
It's from their MX2 line:
www.magicmarine.comAlso, it'll look great on your new N20.