The main seating area looks fine, but sure about the small section with the bay window, perhaps try adding a round coffee table to define the space a bit more.

Function is the word! What functions do you need out of all of these spaces?

The one thing I don't see is a tv. Perhaps your family just doesn't watch? But if you do, create a comfortable set up for it. Looking at the floor plan I can see a wall mounted tv where the piano is shown. Then the area of the "bump out" could hold a sofa table. Place one of your sofas or two comfortable chairs facing tv for ease of viewing.

Do you host a lot of formal dinners? If not, then consider the "dining room" for something else. Perhaps a music room/library. There is quite a bit of space next to the kitchen where the round table is. That could hold a larger dining table, or at least there is plenty of room to add leaves to your round table to fit more guests.

Just make sure the rooms don't dictate to you. You make the decisions how the rooms should work.

Thanks for comments. Good ideas there. We'll play around a bit with furniture and take a few pics. Our TV will be going downstairs in the "entertainment room"