1 night in London- 85K certificate

I will likely have an overnight layover in London later this year from around 4 PM to 2 PM the next day. I will be returning from my honeymoon and would like to maximize the value of my 85K free night certificate from the Ritz Chase card.

Off a quick search the JW Grosvenor House seems to be a great value, but I don't know much about the city itself, proximity to LHR, etc. Any advice or feedback appreciated!