I don't think it's that good either. In the office/guest room downstairs, there is no possibility to place a wardrobe or something similar. Also, only one person can sleep there, right? How does it work with the grandparents (a bigger bed doesn't really fit, at the back in front of the window you could only get in from the front because the room is so narrow)? The kitchen probably has too little storage space for 5 people, and throughout the entire living/dining area, you have no space for storage without blocking the pathways. The same applies in the utility room because of the large window. By the way, for a family of 5, 90% of the time a drying rack with clothes that can't go in the dryer will block the way from the second entrance.
If you only have overnight guests 2-3 times a year, then I would consider, depending on the location of the house, either investing in a good sofa bed or sending the grandparents to a hotel overnight (we did that in our last apartment, hotel basically next door). Then both desks fit into a better-shaped office for that purpose (I find it more pleasant atmospherically to have other people's noises than to work in the bedroom) and you can save space in width in the bedroom upstairs. This works in the bathroom too, where at least one meter is wasted in the middle.