Every now & then I go and treat myself to cocktails at the Ritz
The surroundings are great (especially in the Rivoli bar) and the cocktails are very good indeed I've not yet managed to order of menu, to give them a proper test, but the menu is fairly extensive and the drinks are very well made.
The main thing though is the ambience, how you can't feel a least a little bit James Bond leaning back in one of the huge comfortable chairs & drink a large very cold martini I don't know, of course you should really be drinking a vesper, but who cares (also vespers are very trendy at the moment, I'd be happy ordering one at the Ritz & 1 or 2 other places).
So cocktails at the Ritz, check the dress code, it is enforced, take along a reasonable amount of money (the prices last time were about 10 pounds a drink which for a well made cocktail in central London is not too bad). It helps if you know what you like to drink, order and wait whilst a man in a white jacket brings you a marvelous drink sit back with it & make up stories about the other people in the room.