Itinerary that includes WW I and II sites with teenagers

are you ready for sticker shock when you rent a car in one country and turn it in in another?

a Belgian car will have the registration required for Belgian cities, but won't have the Crit'Air sticker to drive into and around Strasbourg.

If you want to go to Luxembourg and are taking the train to Brussels anyway (driving in and around Brussels is not for the feint hearted, and stay away from those curbs/kerbs. They are stone, sharp, very tall, and completely unforgiving to car tyres/tires.) why not take the train from Brussels to Luxembourg? Do you know that all public transport of any kind, bus, tram, train, is completely free?

If you want to see particularly WW1 sites south of Bruges such as the Menin Gate why don't you have the car in Bruges (not that I encourage trying to park in Bruges, and you'll need to understand the blue and white zones).

There will be so much for the boys to learn on this trip. I am sure they will remember it for many years.

Do you have a particular family connection to the Battle of the Bulge?

Worth visiting is the Atlantikwall museum Raversyde near Ostend / Oostende. Easy to reach with public transport from Bruges, but you can park your car there too in case you have one.
https://www.raversyde.be/en

Certainly worth considering in Northern France and not that far from Ypres / Ieper are the two former V2 launch bases La Coupole and Le Blockhaus near Saint-Omer.
https://lacoupole-france.com/en/
https://www.leblockhaus.com/en

Going to Ypres not to miss is Tyne Cot Cemetery near Zonnebeke and to my opion the Passchendaele Museum there too.

As Nigel remarks it’s good to learn more about Crit’Air in France and where one is needed.
https://www.france.fr/en/article/crit-air-anti-pollution-vehicle-sticker/

There's just so much to do close in around Belgium I can't see driving down to Colmar with the time you have. And I love Alsace-Lorraine. Not only do you have the WWI + WWII stuff, but also Waterloo right there. And Namur, and Charleroi, and Mons...

You do understand that Bastogne is pretty rural? Other than the WWII museums and related stuff there's not a lot of attraction.

Consider taking a detour to Aachen, where there are still parts of the Westwall to be seen, and a major battle took place with the military cemetery to show for it.

Or, if you want to see where the USA was involved in both wars, cut across France towards the Meuse and Verdun. You could easily build a trip across the WWI battlefield from Ypres through the French positions, to where the Americans finally got involved. The battle lines for that conflict were long and relatively stable. In WWII there are very few places like Bastogne, where the fighting was concentrated and localized, mostly the lines moved across to the German border fairly quickly once the Normandy lines were breached.

Thank you for the replies so far! Just to address a question - I have rented cars before and returned them to a different country. It made sense in this case because the various areas I want to visit would be more easily reached with a car. I did not know about the car sticker for Strasbourg and I thank you very much for that! I did not encounter that driving previously in France or Italy.

I do know that Bastogne is rural, which is why I wanted to pick up the car upon departing Brussels, drive to Bastogne to spend a few hours, and then continue on to Ettelbruck / Diekirch, where I planned to be driving to see the museums / cemeteries. I had read that public transport in Luxembourg is free, but I was planning to spend our time just driving in the Ardennes.

I do not have any family connection to any battle sites. I'm hoping my kids don't get WW I & II weary so I need to figure out how to space things out a bit.

I just woke up and have not had my coffee yet ! but I am going to look into the suggestions and I thank you each sincerely for taking the time to give me advice.

Please keep it coming!!

You may want to invest in a copy of this book: https://shop.overlordmuseum.com/en/specialized-books/529-1600-musees-europe-9782918505129.html

There is a large and popular WWII museum & memorial in Turckheim, just outside of Colmar.

Another vote for Atlantikwall Museum. Dunkirk is not far from there, as well. To the east there is an aquarium (I haven't been). And it's at the beach! Maybe you can find a cool place to stay and hang out on the beach. We made a day trip from Bruges and liked DeHaan, but with a car, you'd have loads of options.

"...not too big into traditional museums" Does this apply to WW1 museums?

If you intend on going Luxembourg after Brussels, you'll miss the 2 big WW1 museums in France: Perrone in the Somme area and Meaux east of Paris. Both these places were in the thick of fighting in 1914 and afterwards too, ie the last German offensive in 1918.

On WW2 see the museum in Diekirch. In Lux. City if you've the time are more sites (memorials and cemeteries) related to WW1 and WW2.

I would suggest dropping Alsace. If you want to see Hitler's HQ in France (only one), it's not far from Soissons. It's located in Margival. Guided tours are available there too. I did a couple of day trips (train) to Soissons from Paris Nord but the purpose was to check out WW1 related sites in the city.