The dress
requirements are geared towards all passengers. Most evenings are cruise casual with the expectation that passengers refrain from wearing shorts, swim attire and tank tops to the dining rooms.
Many parents dress their kids in similar attire for dinner. For instance, my son wears pants and a button down shirt or polo shirt on casual evenings. Khakis work well. Although most nights, I left him in sneakers since he was headed to the Oceaneer Lab after dinner. On more formal evenings, my son wears dress pants along with a button down shirt and tie.
Getting dressed up for dinner is a perfect time to take family portraits with your own camera or via the ship's photographer.
I've seen every thing from shorts to suits on children (and adults). Personally, I think a dressy pair of shorts works very well for small children. After all, some shorts can be fancier than denim jeans.
I like to get our family dressed for the dinners on the ship. But then, it's nice to get back into comfortable attire for late night activities such as watching a movie or walking on the promenade deck.
Rest assured that your children will not be turned away from the dining room if they are wearing shorts.
Do what works best for your family's packing limitations, budget and comfort. Also, DCL offers casual dining options for families that would rather skip the dining rooms, especially on formal evenings.
With airline luggage policies becoming stricter, I would concentrate on what you can fit in your luggage without going over the customary 50 pound limitation.
Best wishes for a relaxing and magical cruise.