Antoine's place hits the nail hard when it comes to "location, location, location". Grant Place is around the corner, great food options - many which are open late, great bar options, and amazing brunch places. The place can easily fit two adult people and there is space for two more in the living room.
One point to note: Many buildings in Brussels, including this one, do not have Airconditioning. So if you are traveling in the summer, do check for the weather. You may need more than one fan in the house (there is one fan in the house and we felt it was less).
Otherwise enjoy the hospitality and your time in Brussels at this lovely place.