Yeah, I guess I forgot to comment.

The JW Phuket is awesome! Stayed ther 7 nights and had a great time.

I don't know anything about the JW Khao Lak as it is very new, so it may be difficult finding anybody (yet) who has stayed there. The only thing I do know is that it will be much more convenient should you decide to diving day trips or getting to/from live aboards out of Khao Lak. Check out the location on google maps and it becomes quite clear.