Maybe add a coffee table in-front of the couch decorated with a marble game on top of it.
Personally, I think a rug under the couch would add some character to the room. Otherwise, I think the rooms looks great! Good attention to detail.
You could use some cornice molding, it seems flat between the walls and the ceiling.
Add a wooden toy train in the hallway, something a child would play while their parents watch tv
Personally I think some kind of drink/coffee table would be nice in front of the sofa. Maybe a carpet or something. But looks really nice though already, good job! 
add a huge teddy bear toy model.
Some instrument like Violin or Grand Piano looks great and fills up the overspacious place as well.
a big rug should be nice also you should add some kind of bother between the walls and the ceiling
Coffee table? Looks like you need one.
looks like a gramophone would fit on a nice little side table by the couch, a coffee table between the tv and couch with a lace table cloth and maybe a vase, maybe some a rug in the middle of the room, reminds me of my grandmothers home and she has a porceline doll collection so I think something either on a shelf or lining the wall/hall would give some life to it, maybe bottles or even pressed flowers in photoframes, just like someone who has a life of their own lives there
I highly recommend adding a rug to your scene (it helps more than you may reallize). Nice build by the way!
And yes the sofa has a rug underneath the table is just blocking it and thank you @secretajnz for the idea.
Here are some things I thought of:
- A rug
- A mini table on the side of the couch, you can put the radio there.
- More paintings.
That looks really nice! It doesn’t look like it feels empty either, however, maybe try to increase the size of that clock tower right there, feels a bit too small.