This is a really good idea. Any preparation for risk emergent large scale should take into account a plan for meeting and/or communication in the event of emergency. Not just immediate family, but friends, relatives, allies and anyone else who "needs to know".

Before (if/when) electronic communications are null I think its best to exploit it as much as possible in the meantime. Social networking sites are excellent places potentially to hatch plans and plots for the future.

Having a plan ready will definitely reduce stress and ease anxiety, even if its effect is only limitied.

So also, I plan needs to be ready that admits plans don't often work. Creating situational awareness is also critical. In such cases, knowing what to do when communication seems impossible is radically important.