Have you purchased tickets yet? Might save some time if you flew into Amsterdam and flew out of Brussels. If that was the case, I would do this....
4. Antwerp on way to Bruges
9. Leave Brussels
1. Fly into Brussels, see what you need to and get to Ghent
5. Bruges, day trip to Antwerp or spend one night there
9. Leave Amsterdam
I am a lover of Bruges and Ghent. Last time I was there I spent 5 nights in Bruges during Xmas market time and 3 in Ghent. Never bored. We only spend enough time in Brussels to walk around and see the 3 main art museums and then we are off. We day tripped to Antwerp and couldn't wait to leave. It was a rainy Sunday. Nothing opened really, don't care too much for rubins and the city was under so much construction and because of that extremely dirty (literally dirt pikes everywhere, mud, grit grime). I like Amsterdam too and feel it needs at least 3 days. Bruges and Ghent deserve at least 2 or more days.
If you can't fly open jaw, I would immediately get on a train to Amsterdam from Brussels (sleep a bit) and still start from Amsterdam and end up in Brussels. When I have to back track, I save the fly out city for last.