Or maybe an arrangement like this, with two matching chairs opposite the TV, and a third wooden chair opposite the two chairs and next to the fireplace? Could bring in an ottoman for the other sure if space allowed. In these pics, I'm imagining that the wall to the right holds the TV and the wall to the left is where the door to the terrace is.

Another perspective

I like your current arrangement. For more seating, you can use two longer sofas in the same arrangement. Or a sofa with two chairs as you have it but without the ottomans. That leaves room for a backless bench type of seating to face into the conversation area that wouldn't interfere with the TV. With any options, your seating area is rectangular, so a rug would be fine to use. You may have room for a narrow console table behind the sofa facing the tv, if you place a sofa there.

Beautiful home! The set up you described from your friend would be my obvious first thought. It's classic and I think would be very versatile. However, to me, that fireplace just calls for two oversized squashy armchairs angled in front of it! In that case I'd want a shared arm table of some type between them. If there's more of you (I see baby items) you might consider a smaller U shaped sectional with the fireplace at the center point. In that case I would add a console table behind the back of the sofa towards the dining room entrance since a coffee table would be harder to fit. I also believe you need some type of console table or cabinet along that wall opposite the fireplace. I don't think seating would work there so I think it needs to be cabinetry of sometime. As far as sizing, there is no substitution for mocking it up. Use masking tape or old cut out old wrapping paper into the size of some furniture you are looking at. Practice walking around, view it from different angles, etc. As far as what color for any arm or console tables and whether they need to be dark like the dining room, I don't think you need to match the dining room. From the photos it seems that it will read as a separate room. However, with how much light colors you have on the walls and fire place, etc, I think I would still gravitate towards a darker table.