SM Stirling's Emberverse of course, across multiple post-apocalyptic generations. F M Busby's relativistic Rissa Kerguelen/Bran Tregare saga. Mike Shepherd's Jump Universe (including all of the Kris Longknife novels).

do any of the Turtledove SF series go on long enough to be family sagas?

And of course the combination of Julian May's Saga Of The Exiles with Intervention and the Galactic Milieu trilogy. Paul McAuley's Quiet War quartet. Oh and several generations of George R R Martin's and others' Wild Card series, with multiple families in play!