Thanks for those suggestions, but in the end I was unable to take the flight with the layover.
However I will soon be back in Vienna for a weekend, and as usual the Opera performances are sold out. I emailed the concierge at the hotel I will be staying but he informed me that it is not possible to obtain last minute tickets on the day of the performance. Is he correct, or did he just assume I would not be interested in standng room tickets?
Did you ask him about standing room tickets when you talked with him?
I am pretty sure standing room are still available only on the day of the opera.
John