Disclaimer:
I have searched for a "master" London hotel thread without success.
If there is one, please point me in the right direction and I'll post my question there if it isn't already answered.

Anyway, I am currently looking for a hotel in London for one night on February 23rd. Prices seem to be through the roof, the Meridien is already sold out on SPG's website...?! Is there anything specific going on that day?

My girl-friend and I will arrive at Heathrow and fly out from Stansted the following day. She hasn't been to London before and it's also been a while since my last visit, so we'd like to stay close to the main sights (but ideally also have a good connection to the airports).

I have a IHG free night voucher, but that doesn't seem to be redeemable on that day. I also have 6k IHG points, so that's not very much.

I'm an IHG Gold Ambassador and I have Hilton Gold, SPG Gold (will actually have completed an SPG Platinum challenge that day, but I'm assuming it will take some time for the status to get updated), ClubCarlson Gold, Accor Platinum, Steigenberger Prestige, GHA Discovery Platinum.

I have about 1.800 SPG points, but I will have some more in two weeks, as I'm going to have some more nights with Starwood in the coming days.
But that probably still won't be enough.

I also have a Platinum American Express card with 100k+ MR points.

The larger brands seem to demand at least about 230 GBP per night.
Booking.com offers "The Nadler Victoria" for 120 GBP. That hotel has excellent reviews, but it's not part of a chain and I obviously wouldn't get an upgrade.

I don't know, what would you do?
I don't really feel like paying too much, something up to 160 GBP per night would be nice... Maybe there is some way to use points or make use of some best-rate guarantee?

Thank you very much in advance.