California Dreamin' reminds us that '60s pop paragons The Mamas & The Papas had an appealing new sound, made some terrific records, and left behind a legacy that lives on more than 35 years after they called it quits. This hour-long documentary, originally aired on PBS, has all the standard elements of the genre: interviews (including some from 2004 and '05 with surviving members Michelle Phillips and Denny Doherty, as well as 1986 recollections by John Phillips, who died in '01, and a few brief words from Cass Elliot, who passed away in '74), photos, home movies, and a generous helping of music clips…