Mid to late Verdi is the greatest.
We did a concert performance of Don Carlo with Richard Tucker, Gabriella Tucci, and Cornell MacNeil in Severance Hall around 1971, and I think that's one of the operas I helped to stage manage, making sure entrances and exits happened as they should on my side of the stage.
Two unique memories from that:
It was the one time in my life I sat at a piano on the stage of Severance Hall. I played auditions for the smaller roles selected from local talent.
I also shared driving duties, and my big catch was driving Mr. Tucker from his hotel in downtown Cleveland out to Severance Hall for one of the rehearsals. Just him and me, and what I remember is his being bundled up to protect from the cold, and that he wasn't very talkative, probably very much due to my being completely tongue-tied in his presence.