I have stayed at Brussels Hilton on Waterloo 3 times in the past 3 years. I give it 3.5 Doakes out of a possible 5 Doakes. Never upgraded as Gold but free breakfast not a problem and the quality is good. Excellent shopping area (Avenue Louise as well as the adjacent streets to the hotel), longish walk to the Grand Place and Art Museums (I'd say 2 km or 1.2 miles SAE), close to the subway so no need for cabs to the airport or railroad station.
Minus is that service is efficient but cold, concierge is rather unhelpful and has himself overrated, and the rooms are not large. Also, there WAS high-rise construction nearby that generated much noise around 0730 if you are a late sleeper. It could be done by now as it looked to be in the latter stages when I was there this fall.
JD