I just received an offer from the Sydney Opera House and assume that the Promo Code is generic:
Etihad Airways is the Official Airline Partner of the Sydney Opera House and is proud to fly artists from all over the world to perform here in Australia. To celebrate, Etihad is offering Opera House subscribers a 10% discount on destinations worldwide.
To book, enter the promo code SOHP216.
Offer ends 8 Oct
Terms and Conditions apply. Offer ends 8 Oct 2016. Available for departures from Sydney, Melbourne, Brisbane and Perth for travel until 31 Jul 2017. Not valid on private fares or open jaw or multi-destination bookings. Not valid for bookings on the Residence. Bookings must be made online and payment must be made during the booking process. Changes and cancellation of finalised bookings may incur additional charges. Some flights may be operated by code share partners. Other terms and conditions apply: www.etihad.com/en-au/legal/terms-and-conditions