How could I possibly forget Carrie Newcomer? If you haven't heard of her, do seek her out. She's usually classified as folk, but like Mary Chapin Carpenter and Alison Krauss, she really doesn't belong to just one category.
There's a particular song, "Gathering of Spirits," that might suit a family reunion, especially this lyric:
"let it go my love my truest,
let it sail on silver wings
life’s a twinkling that’s for certain,
but it’s such a fine thing
there’s a gathering of spirits
there’s a festival of friends
and we’ll take up where we left off
when we all meet again."
And this:
"just east of eden
but there’s heaven in our midst
and we’re never really all that far
from those we love and miss
wade out in the water
there’s a glory all around
and the wisest say there’s a 1000 ways
to kneel and kiss the ground"
http://www.searchlyrics.org/carrie_newcomer/the_gathering_of_spirits.htmlI really like the compilation "Betty's Diner," which includes "Gathering of Spirits."
http://www.carrienewcomer.com/carrie_flash.htmlAnd how could I forget "Jubilee" by Mary Chapin Carpenter? It's on the "Stones in the Road" album.
http://www.lyricsdepot.com/mary-chapin-carpenter/jubilee.htmlAnd if you like jazz vocals, you might check out some of those collections on the Verve label (i.e., songwriter collections for the Gershwins, Jerome Kern, Rodgers & Hart, etc.). Those have intergenerational appeal, and of course some of the songs (e.g., "Manhattan" by Rodgers & Hart) have place as a theme.