With so many ways to book, what's the cheapest way to secure a hotel room?

There have been occasions in recent times when I have needed a mid-range hotel room - one in Melbourne, another in Nottingham in the UK, and a high-end room in Athens, Greece. With a raft of booking options to choose from, I was curious to discover which one would deliver the cheapest result.

The answer deeply surprised me.

On the day I needed to stay in the Adina Apartment Hotel Pentridge Melbourne, the "public rate" for the cheapest double room was $234.

If I booked through the hotel's own website, the cheapest price was an "eClub member rate" of $161.58, and this was advertised as the "guaranteed best rate".

But the same room was bookable through Qantas Hotels as a Frequent Flyer "member deal" for only $151.

A hotel can truthfully advertise a "guaranteed best rate" even when a cheaper rate is available elsewhere because booking conditions differ.

In this case, the difference was that the Qantas Hotels deal was non-refundable, whereas I could cancel a direct booking the day before arrival.

And the Qantas deal included frequent flyer points, whereas the hotel itself offered a complimentary reward of the guest's choice. When I joined the loyalty scheme and made a dummy booking, this turned out to be either a late checkout, an early check-in, or a bottle of wine.

Booked through the Agoda app on my iPhone, with an Agodasale discount and another "special discount" (which I always seem to get), the same room at the Adina was only $136. Bizarrely, however, the rate on Agoda's website was $180. On the Virgin Australia website, which is powered by Agoda, the rate was $165 including frequent flyer points.

Go figure.

Some of the more obscure websites that turned up on a Google search were ghost businesses that simply directed me back to better-known providers. No website could beat the Agoda app, even without the discounts.

In Nottingham, I chose the Mercure Nottingham City Centre George Hotel. The public rate was $154. Booked direct through Accor's ALL app, it cost $138. Qantas Hotels offered it for $138, too. Both rates included points, but both were non-refundable. The Agoda app had it for $130. American Express offered $130 too.

When I searched Skyscanner.com, which gathers prices from many different consolidators, the featured rate was $137 through Trip.com - even though the Skyscanner search also found the cheaper Agoda rate. Skyscanner obviously operates its own (commission-driven) ranking system.

I didn't know that.

Finally, I looked at the InterContinental Athenaeum Athens. The public rate for my dates was $258 before tax. If I joined IHG Rewards Club, the room would be $243. The cheapest rate I could find was offered through Traveluro.com, which had non-refundable rooms for $191.

However, the pictures on Traveluro's website were distorted screenshots and the company charged $15 extra for "VIP service" (a customer-service phoneline).

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I just wasn't game.

Then I realised the Agoda app offered the same room for $180, refundable and with taxes included. The problem was, Agoda had only one discounted room, and I needed two.

When I tried to book a room for my kids a few hours' later, the price had gone up to $330.

So, what is the cheapest way to book a hotel? For my purposes, the Agoda app.

Pity about family ...