We just got back from a week in Belgium. Really enjoyed it. I like both Brussels and Ghent over Bruges for more than a day. Train makes it easy to go between cities. We did day trips from Antwerp to Brussels, Bruges and Ghent. YOu can get a 10 card train pass for like 8 euro a one way trip anywhere in Belgium.
Maybe base in Brussels and visit Ghent and/or Bruges? We really liked the walking tour we did of Brussels. Will look up the name if you want.
Bruges is overrun with tourists, but is beautiful.