We did 2 1/2 days in Bruges and really enjoyed it. Stayed at Hotel Navarra, which we really enjoyed. Sites -- Market is great. Get a beer, bacon salad and some mussels, and frites and sit in the market square for a great lunch. Belltower is a great view over to the coast. In no particular order, we visited Stadhuis (City Hall) - well worth a visit. Took canal tour by boat, again well worth it. Groeninge Museum is very good. As is the Memling museum in the old hospital. The churches are worth visiting, if you like cathedrals. Basilica of the Holy Blood is interesting. Folklore museum was an interesting visit, but not worth more than about an hour.
Finally a visit to Bruges is not complete without some chocolate. For us, that means Dumon chocolatier. Fantastic chocolates. Only wish I had brought home twice as much.
Enjoy your visit.