First off, Singapore is an insanely expensive hotel market similar to other large cities around the world like London, Tokyo, and Hong Kong (before all the protests and coronavirus). Expect to pay upwards of $400 AUD a night during peak season for 5 star luxury hotels.
There really aren’t many ways to get discounts on luxury rooms stays per say but it is possible to get more for your money. You could try and book through the AMEX Hotel Collection (accessible to AMEX Explorer cardholders) for a $75 USD Credit and some other amenities, AMEX Fine Hotels and Resorts (for AMEX Platinum Charge cardholders) which grants you a larger $100USD credit, room upgrade if available, late check-out, early check-in, etc. If you don’t hold any of the above credit cards, you can try booking a stay with Virtuoso. Virtuoso is a similar booking site to AMEX Hotel Collection or FHR where you get extra benefits like a $100 F&B credit, room upgrade, late check-out, etc for booking with them. Of course, you have to compare the rates between official booking channels and those websites to see if you are paying more for the privilege of these benefits, but generally, the rate is similar and you’d end up getting extra benefits if you book through one of the above sites. Keep in mind though that elite status privileges typically don’t apply, meaning you don’t earn points and elite nights or enjoy your elite status benefits EXCEPT for AMEX FHR.
The above three sites have a good selection of luxury hotels ranging from chain brands such as Andaz Singapore, St Regis, Ritz Carlton, Grand Hyatt and Conrad to independent brands like the Fullerton Bay Hotel, the Raffles hotel and more. Unfortunately, the Marina Bay Sands cannot be booked through one of these channels.
For Marina Bay Sands, my advice is to just stay one or two nights because soon you’ll be tired of the casino style, huge property, impersonalised service hotel. Imagine staying at the Cosmopolitan in Las Vegas. It’s huge! This means that everything takes a very long time. If you haven’t paid for a club room, be prepared to line up for upwards of 30 minutes to check-in or out. My experience was that everything felt like I was in an airport. However, I woulds still recommend staying there because it was stunning especially the infinity pool. If you booked a stay at the property, you do get access to the SkyPark which would cost you otherwise.
Points purchase sales do happen quite often and I would recommend paying attention to Hilton points sales as you can snag points for pretty cheap and have enough points for a decent value redemption at high end properties.
If you were looking more on the budget side (3-4 stars), the Accor chain has a huge selection of properties and I would recommend taking a look at the Mercure Bugis. In terms of luxury hotel picks, I would say Swissotel Stamford for a cheaper 5 star experience, Fullerton Bay Hotel for a more exclusive feel, and classic luxury can be found at either the Raffles, Ritz Carlton or St Regis. For more modern luxury, consider the very modern AndaZ singapore.
For monitoring bargains overall, I would suggest the sister site of the popular OzBargain website, CheapCheapLah. It features not just travel bargains but all the discounts in Singapore in general.