Just for completeness for those considering WB - B position, here's info about the 330 bunks:

The bunk on the A330-300 is great. Cool, comfortable, plenty long (I'm 6' and was plenty comfortable). Also space to sit up and read, watch a movie on your device or whatever. Not a lot of area to change, but enough. Also, a double set of curtains kept light and noise out when the FAs go by to their area (it's right next to yours). They never woke me up. It's mid-airplane, under the floor. I always slept well down there.

On the -200, it's in the tail, and noisier because it's behind the wing (so you're getting engine noise and I think you're up against the skin of the plane). I used ear plugs on the -200, didn't have to on the -300. It's much tighter when you're getting ready, with little space to change or even put your shirt on. It has two bunks back there, in a row, one is higher than the other one, but they don't quite overlap. I didn't like those bunks as much, but I think they have the same mattress. Also, good luck getting to the cockpit after third break when the carts are out - plan an extra 5 minutes for that!

Just my opinions - I didn't fly the -900, it was all west coast when I was on the 300 and got bumped off before I saw it on the east coast.