For the 27th year, Macy’s flips the switch on the Great Tree: an 83-foot-tall tannenbaum glittering with more than 33,000 lights and 1,100 ornaments. The lighting ceremony includes performances by “I Need a Dollar” singer Aloe Blacc, the San Francisco Boys Chorus, Oakland Interfaith Gospel Choir and the cast of San Francisco Playhouse’s She Loves Me.