We will be on a cruise ship porting in Zeebrugge in July. We will be in port from 8am - 5pm. Do you suggest we see Bruges or Brussels...and why?
Unless there is art you must see in a museum, Brussels is too far and less attractive than Bruges. Nobody at home will ask you about Brussels.
If you had an extra day or two, I’d even suggest seeing Gent, between the other two. But with just the 9 hours in port, definitely go with Bruges. Several worthwhile museums are there, plus a canal cruise, and a good assortment of chocolate “praline” shops. You could even rent bicycles and do a nice ride to Damme and back.
Bruges, hands down. You'd spend too much time getting to and from Brussels when Bruges is MUCH closer to the port. Traveler's interests can be different but we much preferred the compact, old-town center Bruges to big-city Brussels: picturesque architecture; interesting history; good food; a very nice art museum; easy walking... A great way to spend a day.
Spend some time with the website and/or ask for ideas based on your interests. Do note which attractions, if any, may be closed on the day of your visit, and I would expect that parts of town will be very busy.
I agree the Bruges is your best choice. Brussels is too far for a day trip. If you want to skip the exorbitant excursion fee, you can walk from the dock to a tram stop, take the coastal tram to Blankenberge, and then a fast train to Bruges. There are slower, infrequent trains that run from Zeebrugge to Bruges as well, but the locals told me connections are better from Blankenberge.