If you have young children, you should consider appointing guardians to take care of them if you die while they are still young. Even if you have "god parents" we all know that the choice of a god parent is sometimes an emotional decision made at a specific time, usually when your children are very small.
You may find that as your children age, there are other friends or family members that would be able to see to their needs more effectively. If you die and there is no one officially named as Guardian, you may find that a family member will need to apply to court to obtain the right to make medical and legal decisions on behalf of your minor children at what is already a traumatic time. This can be incorporated into your Will.