What sites are you interested in? Two of the segments of the Royal Museums of Fine Arts are currently closed. The old masters collection and the Magritte Museum (sharing an entry point) are open and aren't terribly far from the Grand Place. The museums in the Parc du Cinquantenaire and most of the Art Nouveau house-museums are farther south and a considerable walk away.
I was just in Brussels for nearly two weeks. I was bothered by the construction in the immediate area of Central Station. Vehicle traffic gets through, but some sidewalks to the NE are blocked. It really irritated me to have to walk blocks out of my way when I was pulling a suitcase behind me. I tried using CityMapper for walking directions, but it put me on a route that was heavily cobbled (lots of cobblestones in Brussels). I think Pillows might be really close to the construction barriers, though I'm not 100% sure. I believe the other three hotel locations would not be affected by the construction if you travel directly to or from Central Station. You might run into an issue on the way to the art museums and the Musical Instrument Museum if you tried to skirt Central Station to the east. Walking around it to the west would be fine, I think.
The Grand Place is indeed grand, but it is massively touristy--comparable to San Marco in Venice. Nearby streets are affected as well. It was not an area where I wanted to hang out, but YMMV. I didn't eat in the area around the Grand Place, but there are many options nearby because there's tons of foot traffic.
