Do you have any updated pics of the space since the wall was removed that shows the current curtains? My first thought was that these drapes are much too dark to pull together a coastal feel. I would want a lighter, maybe linen, drapery, a soft natural color rug under the table, and stick with light or white finishes for the furnishings in the room.

Against the look I just described above, I like Tradewind and Topsail from SW for a blue coastal paint. With the current drapery though, I don't think blue would be right. Maybe something more like Silver Strand or Sea Salt? I would absolutely get samples and test in the light though, because the dark grey floor and furnishings are also going to dictate this coming out successfully with a coastal feel.