I'd also recommend a different property for your needs. The immediate area of the Garden Inn is meh, a few blocks up North (but up a hill) around Place Louise and Place Stephanie is a nice upmarket shopping district, a few blocks further South around Porte de Hal it's downright dodgy at night.

..it isn't in Brussels. Regular Uber is banned in Brussels. They do operate a limo-type service, but it is isn't nearly as readily available (or cheap) as you'd expect Uber to be.

There is an okay Hilton right in the Grand Place area. Very touristy, but looks like more what you are looking for.