We will be traveling with our son and his family. They have two boys, aged 3 and 6, What would you recommend doing with them in Bruges and Antwerp?. We will be there during the first two weeks of October.
First of all, ever since they kicked us out in 1830 Belgium is an independent country and no longer part of the Netherlands :-)
There is lots to do in Antwerp and Bruges that’s great for kids, but it would help if you provide a bit more information. You write you’ll be there during the first 2 weeks of October. Does that mean you plan to spend 2 full weeks in Antwerp and Bruges? If so, that might be a bit too much. Or do you plan to visit other places? If so, which ones? How do you plan to travel around? By public transport?
If the weather is good, I remember a wonderful panorama of families in the Rivierenhof park on Sunday afternoons. I don't think you can enter the (former) silver museum castle there, but walking the courtyard would be fun for children anyway. It's a challenge to get to without a taxi, but the outdoor sculpture park (Middleheim), a bit remote, is a treat for both children and adults. It is quite big, so I'd research a place to eat nearby before going. Best chocolate in Antwerp used to be Burie, local maker. Goosen's bakery nearby, great smells even if a long line. (Have not been there in ten years ... )
The roof of the MAS museum used to be open to all without admission to the museum. I guess looking over the parapet is less fun for short people ... This is a good museum for kids because every floor is a different "collection." Antwerp is full of interesting things to see. Will you have a stroller? The kids would want not only waffles, but the local equivalent (much better) of fried dough, smoutebollen I think. (choking hazard, like donut holes???) Frites (french fries) are a Belgian institution. Make sure they have tomato ketchup available before ordering! In general, I found food better in Belgium than in the Netherlands.
Do not overlook the compact botanical garden (behind the Magdenhuis museum) which has no admission. It's maybe too far to walk all the way, but you could show them the pedestrian tunnel under the river. (Escalator access, if I remember ... )
Thank you for your ideas which I’ll definitely check out. . Here’s some more information. We will be in Bruges Oct 5-8. Then we will be in Antwerp from oct 8-11.
In that case I would definitely recommend you to take a day trip from Bruges to Ghent. The Gravensteen castle right in the city center of Ghent will definitely appeal to your boys.
In Antwerp I suggest a visit to the Zoo. My niece and nephew of similar age also enjoyed Chocolate Nation very much https://www.chocolatenation.be/en?gad_source=1&gbraid=0AAAAAC5KGIt9PWp05r9HHEgdrsHo7o0ub
We did a day trip from Bruges to the coast to see the Atlantic Wall Museum (a bit grim for young kids). We followed that up with some beach time in DeHaan. We were a little earlier than you, and the weather was already very windy and a bit chilly, but who doesn't love a beach day?! Looks like there is a water park and a nearby aquarium. My point is, take your inland kids to see the sea.
Definitely take the canal cruise in Bruges and I agree that you should at least a day trip to Ghent. It is such a great little town. As a family you should go see the Ghent Altar Piece at St Bravo's. But definitely the Gravensteen castle. The audio is totally cheeky and inappropriate for kids so that's not needed. The castle is a fun thing to explore. But it's not like the US; there's no railings in places where there should be some. Right across from the castle is In Choc Gent. I thought it was going to be just a chocolate shop, but it's actually a wonderful restaurant, and delicious.