We stayed with two adults and a teen almost 16 years ago at the Hilton Park Lane. Was a bit of a hassle to book with points for 3 people. Had to be transferred to the Scotland diamond desk to book it. The lounge was nice, and the hotel was nicely situated. Hotel was otherwise nothing spectacular, and no upgrades were forthcoming.
I can honestly say that we enjoyed out previous stay at a nice house, pre Airbnb, in the late 90’s much more. There are some locations that points are great to use, but I don’t find that the case with Hilton and London.