Split the private key using Samir's Secret Sharing algorithm and give several trusted parties a fragment. For example, a 3-of-5 scheme where you give a fragment to a spouse, friend, family member, lawyer and bank deposit box. Any 3 fragments can be used to recover the private key. A short instruction on what Bitcoin is and how to use the private key you can spread more liberally to your beneficiaries.
Something like this along with Armory. And use
KeepassX to manage some of the sensitive information.
Or pre-craft the transactions, but do not submit them to the network, and then have them provide a public key they control that is in a cold wallet or give them the private keys to the txouts. This is handy because you can pre-craft multiple transactions for the same bitcoins and it is just the first that gets submitted that actually matters. So you can have scenarios pre-crafted.