Its just behind Knightsbridge, less than 1 block from Harrods and Harvey Nicholas and the front looks out onto a park. Its about 15 minutes drive from the theatres in one direction and The Royal Albert Hall is about 10 minutes in the other direction. Its also not far from Mayfair and Bond Street where all the high end designer shops are located.
Agree on the older hotel front - for my husbands birthday I did room bidding on priceline and got the Metropolitan for one night and the Waldorf for one night.
Both 5 stars, got both for under £130 but the difference was unbelievable - The Met was modern, light, nice smelling, everything worked. The Waldorf was pokey, dirty windows because the way it was designed meant no-one can clean the inwards facing rooms, the bathroom had grotty grouting and they obviously never moved the bed as there was an old newspaper and a dirty video underneath!
I would say the Met was the best I've stayed at in London, probably beating the Mondrian, but then I tend to not do the expensive ones that often
Definitely recommend Priceline if you aren't too bothered about choosing within a star rating or want luxury on a budget
The Dorchester is our Favourite London hotel by miles. Lovely rooms, Fantastic service and the staff are lovely, they can't do enough for you, nothing is too much effort. It is a bit pricey though!