When in Belgium, the Floris bar is quite the nice place to go when in Brussels. I love the place and the staff. Unfortunately, though, the place can get a little crowded and rowdy, due to the high tourist populace of the neighboring Delirium Bar, and I am the type of person who dislikes crowds.
But I found one of the best places I have ever been to, in Gent (about an hour north of Brussels via train).
It's called 'Old Fashioned', and that's exactly what it is. You walk in and it is dimly lit, the two smiling bartenders are adorned in Belle-Epoque-era clothing, there is old jazz/club/cabaret music playing softly in the background.
I went in at around 23:00 after a concert in Gent and was surprised to see such a calm, relaxed, yet fascinating place. I did not really know what their selection was, so I asked the gentleman to bring me anything 'decent'.
He brought me an Un Émile 68 bottle with an accompanying carafe full of ice-cold water.
The only issue I had was that the place is expensive. My glass cost about 11 euro, whereas I know that I could get the same drink at Floris for about five. However, the atmosphere of this place was top-notch, and I would highly recommend it to anyone in the Western European area who has a little bit of cash to part with.
I did not see much of their selection, so I am unsure as to how their menu looks, but I would recommend anyone to go solely for the purpose of stepping in a time machine for an hour or two.
Here is a video of these two gentlemen at the establishment (odds are you will be there during nighttime, though, and the place will have an entirely different feel to it).