I think it would be good to swap out the formal chandelier for something similar to the red one posted in the above photos, one that reads less formal and more ''workspace''. I also think painting the whole area one color such as solid white and removing the drapes and just using blinds. I also like that idea of the shelf up top to display models. If you hang any I would only hang them in the center of the ceiling above the table which would work well as the workplace, some swivel chairs would be nice. I'm thinking of short book shelves along the bottom half which leave you a top shelf (counter height)and lower shelves for storage and display and using the open wall space for classic aviation wall hangings that are flat such as signs and framed posters and such would be nice. Floor to ceiling shelves would really close the space in but I think the shorter ones along the lower portion would be sufficient and also hide the formal trimming of the room, but it would be nice to see along a whole wall, not just a couple short shelves here and there in the room, that would make it look very unorganized. Cool, let us know how it comes along!

What are the dimensions of the room, and the width of the bookcase? Could the bookcase go on the wall that we can't see, which is opposite where it is now? I ask because it seems that you have no room near the chairs, and I can't tell about the sofa, for end tables and any lamps. How much longer is the sofa than the 2 chairs, side by side? I'm asking that to see if there is more room for the other 2 chairs, rather than the sofa. Something along this line -

Can you not put the din table in front of the fireplace? My dining room has a fireplace in it and it's most grand. My living room also has a fireplace. They are great visually in both places (we have yet to get them working again, but it's on our list). That said, on the other hand, I honestly like the status quo better than the proposed rearrangement. Keep in mind that a bigger kitchen isn't necessarily a better kitchen. If you want more kitchen, I'd think that expanding into the breakfast nook area would be better. Also you could consider opening the wall to the dining room. Designate between the spaces with an island/peninsula with a wine rack or something.

Here are some ideas for an elegant sitting room: This is called a reading alcove! I found this a very elegant idea due to the curved sofa, wall color, and other decor.