We had a very strong steer from one victim's family that they did not want a die-in to be part of POP so we have kept POP itself about celebrating the potential of cycling, while respectfully marking deaths with a minute's silence.
Die ins and ghost bikes can be a strong statement but if dealing with a particular death (rather than deaths in general), I feel that they are stronger if the approach to be led by the family and/or friends. Oxford's Broken Spoke for instance have been leading the way after a death of one of their friends/colleagues (http://bsbcoop.org/the-story-of-change-continues/) and the fact that they know her makes it much more raw and moving. Stop Killing Cyclists, who do the die ins in London, try and have family members involved too.