I have a list of important passwords stored away in a safe for when I die. This includes my coinbase account. I will add my multibit password to the list too. Thanks for bringing this up.
It would be useless if your passwords just be laid in your safe, non bitcoin user cant understand it 
People that don't store their passwords for their loved-ones to find if they die, will have their Bitcoins vanished. They will allways be in the blockchain, yet never spendable. You reminded me to explain it to my wife (again) Encryption isnt really her thing 
Atleast we have to mind this thing 
I think you should make a 'procedure to how open your bitcoin wallet and use bitcoin' for her. Just like the precious metals in my closet my children will open my trunk and go through my things, find ounces of silver and gold and paper wallets full of bitcoins that are hopefully worth more than the precious metals.
Then have you introduced bitcoin to your children?