At first glance, I like the design with the L-hallway, the room under the stairs, and the secluded little guest room. This is a purely emotional observation.
The following caught my attention and has partly already been discussed:
Children’s rooms: By “today’s standards,” they are quite small. However, I agree with you that they are absolutely sufficient nonetheless. It’s not as if you’re giving yourself a mega spa and squeezing the children together—the ratio of the rooms to each other seems coherent to me. The upper children’s room has an awkward shape due to the wardrobe in the study. I would rather resolve this space conflict in favor of the children’s room. The children’s rooms gain space if you also make the guest room accessible to the children, for example, for everything that happens at a desk. Saving a desk in the children’s room brings a lot of space for playing. When the children are a bit older, you can place the sleeping area one floor higher, and the space under the bed becomes additionally usable.
Guest room: Just regarding the furnishings here—if this room is supposed to relieve the children’s rooms, having a constantly set-up bed (although the furnishings aren’t finished yet) will be a bit tight. A classic case for an intelligently built sofa bed, or very 70s, a fold-down bed from the closet. If guests don’t stay long but rather just occasionally for one or two nights, that is completely sufficient.
Dining area: Like , I also feared that it might be too tight. A bench would solve that, as you also write.
Pantry: What I like is that you give the pantry sufficient space. This naturally creates a strangely looking block on the kitchen plan. I find that completely okay. Only the arrangement of the kitchen island facing partly toward the wall is a bit unfortunate—but I count that as part of the unplanned furnishings.
Storage space: The need for storage is very individual. We consciously omitted storage space when building to maintain better order and not accumulate so much. But that was the second build after children. With children, it’s a bit different; much storage space is needed. It would be sensible to consider what is stored inside, what outside, and the quantities involved. The small strip in front practically cries out to be used as a bike house and garden shed.
Slanted wall at the entrance: I had the same idea as . Simply leaving it out is nice. However, that way you get the scent of the kitchen throughout the whole house. Therefore, I suggest a glass solution that replaces the doors to the kitchen and living room.
All in all: I think you have been presented with a good design proposal that meets your requirements.