My recent trips to Washington DC and now Brussels give me the opportunity to compare impressions of those two capitals of almost continental dimensions.
First the commonality: Both places are quite obviously centres of administrations with their respective large scale building complexes. I'll freely admit that I prefer Washington's often neo-classical architecture (as designed by a Frenchman) to Brussels' more recent modernist stuff which is entirely devoid of character, I think. The whole quarter around Schuman is just plain ugly, I am afraid.
However, as far as city life & culture go, Brussels seems to be the far more interesting place. I get the impression that while it may not be immediately accessible, Brussels has a lot of hidden treasures, not least culinary ones. Dinner at a Michelin ornate restaurant was certainly good, but an ordinary Brasserie I discovered while walking past was just as good, and the whole dinner probably cost as much as one course in the Michelin place. Interestingly, the Belgians seem to be entirely unabashed public smokers - how unselfish of them, what with that evil trend of increasing longevity & dire state finances.
Incidentally, the Belgians seem to be taking issue with the Guide Michelin's rather spectacular divestiture of some stars, which I cannot confirm online. Also, I had some doubts as to the Economist's ranking of Belgian chocolate over Swiss, but having invested in and thoroughly sampled the delights of Marcolini, I gladly concede defeat. Try the thyme & orange flavoured pralinés - a bit like those Harry Potter sweets, minus the spectacular effects. Fabulous!
Finally, if you are interested in art nouveau, then Brussels is certainly your destination of choice. The Horta Museum is a must, which cannot really be said about the Horta Pavillon, which is a small neo-classical structure housing an apparently scandalous sculpture about the human passions that caused the pavillon's indefinite closing only three days after its grand opening in 1889. I am really curious now as to why that might have been so scandalous back then, but the place is tightly shut during the winter season.