I think an entryway is a good idea, thst or hallway. If u have a guest room, that might b a good option. I’d def not put it in the dining room if it makes the kids sad.

I think hallways that lead to bedrooms are a nice place to hang family mementos, baby photos, and perhaps create a picture collage wall, including perhaps your shadow box.

That way, family sees it daily whereas it's not a topic of conversation for every guest and repair-person who enters the home, and doesn't become a mood-setting item for family/friend gatherings.

I have a friend who calls the wall in her hallway her "ancestor collection" and indeed has old photos of the family home from generations ago, an old love letter framed, black and white photos, military ribbons of some sort, photos of childhood pets... and the like.... and the frames are well done and anyone who gets to see it absorbs the idea of the history behind it, and it informs of the family's interest in their generational history. That's what I can see the value in.

I think that if the loss is fresh for you and your family, it may take some time to decide where you want to place this item, or any other item(s) that bring your father's memory to mind. It'll take awhile to decide how you want to do it, keeping in mind that other people live in the house and how they wish to see him honored. It isn't the same for every person. It's a challenging time. I'm sorry for your loss.