As an example you can stay at the Sofitel Melbourne on Collins in January for $177/n or Sydney $165/n.
The deal is valid at 74 hotels worldwide.
To get this deal you need to be a Le Club Accor member. Membership is free http://www.sofitel.com/gb/leclub/index.shtml
Terms & conditions
Terms and Conditions (blackout dates as well as other restrictions may apply: please read the following). Guests booking Sofitel Exclusive Sales confirm they have read and accept the following conditions:
Offer is subject to availability at participating hotels and is valid for bookings made on http://www.sofitel.com/gb/private-sales/index.shtml between 7/10/2013 and 14/10/2013, for stays between 18/11/2013 and 31/03/2014 inclusive.
The 40% reduction per night is calculated on the basis of the Premium rate (or the Best Flexible Rate for hotels that do not have the Premium Rate). This offer is for accommodation only.
The offer is for physical persons only and is limited to 7 rooms per booking.
The offer does not apply for groups (more than 7 rooms).
The offer cannot be combined with any other special offers or advantages.
The pre-payment by credit card of the full amount of the stay will be debited at the time of reservation. The amount pre-paid is not reimbursable. Reservations can not be modified, cancelled or exchanged.
Among participating hotels, some properties require a minimum stay of 3 nights. Moreover, some blackout dates apply.
http://www.sofitel.com/gb/private-sales/index.shtml
http://www.accorhotels.com/gb/hotels-offers/promotion-19403-…
EDIT:
I have found a list of properties and blackout dates.
http://www.sofitel.com/pdf/private_sales_cgv.pdf
Apparently rebate sites like https://www.mrrebates.com offer around 6% cashback also.
Looks like a good deal