I downloaded a house that has long open floor plans...

Can you post a photo of it?

Sure here is the upper floor.

Check out my screenshot from #TheSims4! pic.twitter.com/rxqq8u6nL7

— Heather (@BatmanFanGirl) May 27, 2020

And the bottom floor.

house #TheSims4 pic.twitter.com/wTetdCAna9

— Heather (@BatmanFanGirl) May 27, 2020

Usually when I have a big area on the top floor of my house, I put a reading nook, kids' play area, or a gaming area. Or if I really want to fill the space, build an extra room, or just open it to the bottom floor. And when all else fails, I just make the house smaller.

On the second floor, is that a door going to a balcony? That could be an office.

Okay i've done some more work but I still don't like the empty space in the middle. It's the main walk way though so I'm not sure what to do with it.

Check out my screenshot from #TheSims4! pic.twitter.com/7qwlWG1CyD

— Heather (@BatmanFanGirl) May 28, 2020

Floor 2 #TheSims4 pic.twitter.com/CUVWRGuRZw

— Heather (@BatmanFanGirl) May 28, 2020

"BatmanFanGirl;c-17517602" wrote:
Okay i've done some more work but I still don't like the empty space in the middle. It's the main walk way though so I'm not sure what to do with it.

You could build a square room in the space between the stairs and front door, and add arches or big glass doors in the walls leading to the living room, dining room and the hallway behind. Then you could leave a small hallway space and build another smallish room in the back where you have the round sofa.