I assume you'll be taking your car? Otherwise, if you mean the In Flanders Fileds Museum in Ypres, that's quite a distance from Bruges.
In case you're not aware, Brussels, Ghent and Antwerp are Low Emission Zones, so you'll need to register your car in advance. I don't drive so don't know much about that, but the issue has often cropped up on previous threads.
Agree that there's more to do in Ghent than in Bruges, though both are lovely. I'd definitely fit in a day or two in Antwerp if you can as it's a wonderful city and would be a good contrast to Bruges and Ghent. There's so much there: historic centre, Museum aan de Stroom (MAS), boat trip round the port area, botanic garden, pedestrian tunnel (the Sint annatunnel) under the River Scheldt to get to the Linkeroever, from where you have a view of the cityscape.
Trip on the Kusttram, the coastal tram mentioned by PP, is also worth doing.
Have a great trip. Belgium is such an underrated destination in my opinion.