Our floor plan... please help with optimization.

Even with shelving systems of 40 cm each, it will be more of a walk-in closet rather than a dressing room where you can turn around. You also have zero daylight... I don't find that productive. Better to do without it and integrate the closet into the bedroom. The hallway is too long and winding... I would probably move the stairs closer to the entrance (about 65 cm), place the WC on the stair side directly on the entrance door wall, then a utility room for technical equipment, then the stairs, then a laundry room for clothes (although that might be a bit tight). The bathroom upstairs will then be smaller - but that's not a problem with a reasonable layout. I would align the upstairs bathroom wall with the bedroom wall (that's exactly about 65 cm), make the children's room correspondingly larger, make the dressing room smaller and access it from the hallway - put in a roof window, cabinets on the right and left. You still have a closet wall in the bedroom anyway. Kind of clear what I mean? Otherwise, I can sketch it out later...