Without seeing the rest of the room, it's difficult to say, BUT a 129" sofa is almost 11 feet long, and in a room that is a bit over 13 feet long, it sounds waaaaay too big! Normal sofas for normal sized rooms run from 6-8 feet long. I think you can do better. Post a dimensioned floor plan and perhaps we can help you furnish the room with human sized furniture.

That is a very nice looking sofa but it sounds like it might be a bit too big :(

Would it be the chaise side near the step down, or the non-chaise side?

You might want to provide a bit of a floor plan as it's not clear to me how it will divide the living room... also, for your own purposes, you can use masking tape to mask off the area on your floor and see how it works out in terms of walking around it.

30 inches is definitely too narrow a walkway.

HI, another photo of the room showing the step down could help also. In some houses it's a full length step (width of room) in others, just 3 or 4 feet. I feel that might make a difference.