The Hyatt is fabulous but REALLLLLLLLLLY expensive.
Most restaurants are costly on Xmas day.Its a really long way from anywhere and I suggest that you sleep and have a lovely Boxing day lunch at the Hyatt or the ANA as we have the Sydney to Hobart yacht race starts at 11am or is it 1pm on Sydney Harbour and EVERYONE is out that day and its REALLY Xmas day on 26th for U!!!They are still taking bookings here now so you should be OK.
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Hyatt Diamond/Hilton Diamond/Starwood Platinum/UA1K-Ansett-WHITE/Qantas-WHITE