Brugge is about an hour and a half from either Antwerp or Brussels. It's a great day trip. Head over to Brugge around 10, have lunch over there. Walk around, have some dessert, then head back. There's trains from the central stations of either city and they head directly there. No need to switch trains.
Brugge used to be a major port hundreds of years ago but trains and other things killed it. It's been resurrected though as a medieval tourist destination. It's got an old world feel and being an ex−port town it's got canals running through it so I can be very scenic. Highly recommended.