Even persons with Living Trusts will normally have a Will. The "pour-over" will typically provide for all the probate assets to be transferred into the trust created during his or her life, and distributed according to its provisions. In this way, assets that were not titled to the trust, or which have been removed from the trust inadvertently or purposefully, will still be covered by the trust's provisions. Your Will is the proper place to provide for the selection of a guardian and/or conservator for the decedent's minor children or incapacitated spouse or children. Many people also choose to declare their preferences for burial arrangements, organ donations and other post death concerns in the Will.
A Will is the instrument used to create a Testamentary Trust, where that is the appropriate arrangement. It may be advisable (for the reasons described above) for even the Grantor of a Living Trust to arrange to have some assets taken through probate court proceedings to cut off potential creditor's claims. Finally, the preparation of a Will is normally much less expensive than the preparation of a Living Trust, and may be all that is necessary for persons with modest estates and ordinary wishes for distribution of assets after death.