Bruges is very beautiful but is a little bit boring with not sooo much to do. We think it's more for the tours with their big buses full of Chinese tourists. You won't discover how Belgium really is by just going to Bruges.
Personally, we suggest you to go to Ghent. You can easily spent 2 days there! It's a very trendy and bustling city with a lot of cool things to do. Especially in the summer months, when you can sit at the Korenlei/Graslei and enjoy the beautiful weather between the university students. Ghent is perfect for culture, history and discovering hidden gems.
If you want to, you can easily spent another day in Brussels. The two cities are 30mins away from each other by train. The Central train station is right in the middle of Brussels and very convenient to see all the touristic places like the Grand Place or Manneke Pis. Brussels is great to see the real Belgium with its blend of diversity and cultures!
If you want some tips, you can always contact us. We both lived for 5 years in Ghent and Thomas is from Brussels.