All these suggestions are great. The Conrad is probably the best hotel in Brussels. If you do stay there, don't be shy to ask for an upgrade to a suite. They are very accomodating about that. I wish I could remember the room number. Will did up my folio and let you know at the Rudifest in SF (hopefully) They have a great room service breakfast too. There is an egyptian gentleman who works the phone lines and he can make just about anything/everything squeeze into a comp continental breakfast.
Hilton's not too shabby either. They were running weekend promo's at these hotels for under BEF5000.