I second the motion on Merritt Herring's version of "Who Will Sing for Me". For my mother's memorial service we used Forever Young by Bob Dylan, and for my father's memorial we used Across the Great Divide by Kate Wolfe. We used Amazing Grace at both services. Most people know it so even folks who do not usually sing in public join in. Another song I've always liked is Awake, Awake to Love and Work. It is in the UCC Hymnal and would sound great with Sacred Harp type harmony.