"Alleluia" is a wonderful option for a majestic introit to open a morning service or a concert with singers positioned around the sanctuary/auditorium.  Approximately one minute in length,  the choir may sing through the piece in the back of the congregation/audience, then proceed to the front while pianist or organist plays portions or all of the piece, and once assembled, the choir may sing through from the beginning or doing second repeat which goes to the Coda.