I've had a wonderful week in Brussels at the Marriott. I stand by all my earlier comments. I would also suggest if you have some free time take a new tour offered by BrusselsCityTours (which can be booked on your room = points). It is called Hidden Treasures of Belgium and covers the Walloon area, which is not easy to get to unless you have a car. The tour covered the Castle of Modave, Huy, Namur, and the amazing ruins of the Cistercian Abbey at Villers. The tour guide was fantastic. On the way back she added another stop -- at Waterloo.
A tip on language. First of all, everyone speaks English in Belgium and the Netherlands -- they are required to take it most of their school years. The French-speaking areas (Walloon and Brussels) are now outnumbered by Flemish-speaking parts of Belgium. This is a reversal of what had been true for centuries, and it has led to rising tensions and calls by the Flemish for separatism. If you speak French, do so and it will be much appreciated in Brussels (the only officially bilingual city in Belgium) and Walloon. Otherwise speak English. A colleague told me when he went to Leuven, he noticed the strong separatist feelings there. As my tour guide said, people in Bruges and Ghent don't mind French speakers (because there are so many tourists), but it is better in any other Flemish area (e.g. Antwerp) to speak English unless you happen to be fluent in Flemish/Dutch!
The food in Brussels is, in my view, the best in the world -- or at least Europe, and that comes from someone who has lived for years in France. However, I have noticed significant changes in the area around the Grand' Place with its restaurant streets. In the 80s I had two of the best meals of my life there as a walk-in. But the quality has gone down with a few exceptions, and the prices have gone up. Plus it is very crowded. I suggest walking 2 blocks in the opposite direction from the hotel and you'll be in Place Sainte-Catherine. If you like seafood, this is the place to eat -- it's right next to the Fish Market, which brings in fresh fish every day. I had three wonderful lunches at different restaurants there. (What I typically do, since lunches are often less expensive than dinners, is to have a very nice lunch -- then in the evening enjoy the appetizers and desserts at the Marriott.). I ate at La Maraichere, Rugby I (not a sports bar, despite the name), and La Huitriere. The latter was by far the best among very good restaurants. Just look for where most of the people are sitting in these side-by-side restaurants and you'll get a sense of which is best. I include photos of sole meuniere from Rugby and lobster in champagne sauce from Huitriere.
Finally, the Musee Royale des Beaux Arts is one of the best museums in the world. It has a phenomenal collection of Flemish art from the late Middle Ages when Burgundy (which included much of Belgium and the Netherlands) had the richest court in Europe. Usually, I don't spend much time in art museums because I'd rather see actual historical sites. But I spent 4 hours here, most in the 'ancien' section. It includes the works of Rogier van der Weyden, Brueghel Younger and Elder, Hieronymus Bosch and many others. But they also have some great modern paintings, including Jacques-Louis David's Death of Marat as well as late 20th C. art.
I think it was Rick Steves who said in his Belgium guidebook that Brussels was 'short on sites but strong on ambience.' I couldn't agree more. It is a city that you really come to appreciate the more time you spend here.