I think 3 nights in Bruges is too much. Although it is very nice (and I often go there with visitors that come and visit me in Brussels), I would not spend more than a day there. For Belgium, I would therefore maybe get a hotel in Ghent, and do day trips to Bruges, Brussels and Antwerp and spend a few hours in Ghent. Each of those is just half an hour or so by train from Ghent.