Complex sentence: She sang with a succession of top vocal groups--the Norman Luboff Choir, the Pete King Chorale, and the Ken Darby Singers among them--and she appeared on most of the popular television variety shows during the 1950s.
Split into simpler sentences: She sang with a succession of top vocal groups, including the Norman Luboff Choir and the Ken Darby Singers, among others. She appeared on most of the popular television variety shows during the 1950s.