There is no better room in London for a considered drink than a great hotel bar. They are grand without being stiff, open to anyone dressed for them, and built for the kind of evening that has nowhere in particular to be. You do not need to be staying; you just need to walk in like you belong.
Our guide to the best hotel bars in London is where to begin, and it sits within our wider pick of the best bars in London. Many of the finest are attached to the best luxury hotels in London, and a few do champagne better than anyone, as our guide to where to drink champagne makes clear.
Go early for a seat at the famous ones, dress for the room, and ask the bartender what they would make you. At this level, it is always worth hearing.