This is typically more of an issue at the 3* level (being more like a 2*/2.5*) and at the 5* level (more so being like a 'nice' 4* hotel)... but if this is a concern then probably a good idea to stick with a hotel that shows a good user review rating by previous guests.
With the above noted, how about this offer (as with the others, confirm your dates on the landing page of the provided links):
5* Knightsbridge - Harrods for $197
No Smoking Rooms/Facilities
==> best guess for this one would be The Hari London. While i feel very good about this guess, should it ultimately prove to be something else, this offer shows an excellent 9+ user review rating by previous guests, so it should be a great stay even if something other than The Hari London
Does this work for your needs? If not, let us know all zones that are acceptable for this trip as well as your maximum budget (per nite before fees/taxes)... and also know what you don't like about The Hari would be helpful as it would give us a better idea of what it is that you are looking for.
Please remember to return to BetterBidding and use the PRICELINE and HOTWIRE links on the board to begin your travel purchases... or thru our sister site MAPSandHOTELS.com for your regular rate purchases.
Let us know how it goes or how we can be of further help.