I’d experiment with items I already had. Try bringing a couple of chairs and table/ottoman into that area to see if the “flow” and feel remains appealing to you.

I like the upholstered armchair idea. Just keep in mind - if you get swivel chairs, the kids may use them as their new play toy!!!!

Agree with chairs and table also a floor lamp and rug make it a reading "nook"

IMO you need to very careful you do not visually block off the large entry that you see .it will take some trial and error to see how large the chairs can be and what size table to sith with them. I usually use a floor plan to start but always keep in mind what works on a 2D plan might not in real life be visually appealing.If it was my space I would remove the bookcase and have a proper extra seating area since it really looks like mostly stuff that could be stored elsewhere. Then on that wall a large pievce of art that to me would be an improvement

What a cool space! Love your front doors and bookcase.

I don‘t think you can go wrong with any of your options — I’d just think of what would be used most (comfortable). For me, it’d be a chaise (I miss mine), but for others, two chairs might be more useful.

Please update us with what you do!

Patricia Colwell Consulting, that bookcase was expensive and intended to create a library, my husband would kill me if I removed it, and I can't tell you how much wall space I already have that needs art, for which I'll need to rob a bank😂