(hypothetically) When I die I'd like my children to have all my bitcoins. So I was thinking of writing a will to give each of them equal amount but to make it more fun I'd hide the keys from my wallet and make it a quest.
This is really a good thinking but here I am thinking quite different from you because it is more better to explain them for the Bitcoin instead of giving them the address of Bitcoin private key , Because if you will teach your children for the Bitcoin that how to deal and how to manage and how to make in wiseful ways then they will be able to use in better ways of the Bitcoin that you will make before the die .
If you will ask for the private key then I will suggest you for the print out and then put it at safe place and tell your children how to use it to get in online .
The very reason why we save and hold bitcoin for long is for future , for having a comfortable life so why make it hard for them. That's right to teach them ahead of time if they are capable already in understanding things for are savings not to get wasted.