Great !
Ground floor:
To grow up the rooms, you can install between Office and living room few industrial windows like these :
with or without door.
First floor:
You can advance the door of the master bedroom near stairs to have bigger surface and not for hallway.
I like very much the idea for the office! Also the other one.
Should I leave the door for the office near the stairs, once entering the house, or should I remove it and leave only the access through the living room?
Imho I should leave the door :).
