Edit: I'm going to have to retract my comments about cheapest price being on official hotel brand websites. I did a cursory search and find many cheaper options on Hotel Tonight (and expedia) for same day reservations than the brands, and while I haven't looked at all the brand's best price guarantees, at least IHG's exempts them from having to provide the lowest price within 24 hours of checkin, so it seems like a loophole to let them dump rooms for cheaper on third party websites day of arrival.
I just pulled it up for Seattle and the Kimpton Monaco is up for $115, $140 after taxes and fees. From the Kimpton website it's $208 or $264 after taxes and fees. So about half off, pretty good deal! This was just the first one in the list, there may be better deals.
5. Find a Lower Rate. If you find a lower rate on an eligible, non-IHG website within 24 hours of making your reservation on the IHG direct channel, and it is more than 24 hours before the standard check-in time for the hotel where you made your reservation, tell us about it by completing and submitting the online claim form (“Claim Form”). We will verify the lower rate by comparing the rate found on the IHG website or mobile app with the rate found on the non-IHG website for the same hotel, room type, stay dates, number of guests, and cancellation policy.
I'm actually shocked that they would do that, because now I will definitely shop around, I had erroneously thought their best price guarantee would save time.
Same price across all 3 sites.
Chances are, if you see a price lower than the major travel sites, they're losing money. In this case, they're the same price.