I would put the piano on the 17 foot wall with the back of the pianist near to that jog in the wall the defines the separation of the spaces, and the pianist facing the window when she/he is seated. That leaves the piano's open side facing into the room. That way the piano is not right in the center of the room. When I played I always liked not having people seated behind me but rather being in a corner with my back closer to the walls. Just my personal feng shui! Gorgeous space -- gorgeous piano!

I'm remodeling my condo and planning to use my dining room as a combo dining room/office. My dining room is much smaller than yours but here's what I'd do if I had your room. Use the table as a desk. If you need to protect the table, get a glass or other protector. Replace one of the chairs with a high-quality office chair with carpet casters. Replace that small cabinet with a credenza for all your papers, folders, and printer.* If you don't mind modifying the table, install a covered electrical outlet. If you need a computer with a large screen, get an all-in-one (example) instead of a desktop or laptop and separate monitor. Make sure all your peripherals (mouse, keyboard, printer) are all wireless. When you want to dine, just move the all-in-one, peripherals and papers to the credenza. *If you want to get really fancy, get a credenza large enough to hold all that stuff plus the all-in-one computer when it wasn't in use

A couple of ideas: 1. Two separate areas. Similar to this plan, but the chairs closer to windows. And instead of a dining area on the other side, a bookcase against the wall with a comfy seat (oversized chair and ottoman, chaise, etc). Two area rugs, one for each seating area. I think a sofa/sofa table as a room divider would really balance it nicely, be cozy, and look better than having furniture up against the walls with no distinct intention. 2. Having a major feature be the nucleus of the room, and decorating around that. A large bookcase unit against the wall facing your foyer with a seating area in front, and a couple of chairs, chaise, etc in front of windows. Art and maybe a console table along the farthest wall. One large area rug, lamps, etc.

Oh lucky you! I would LOVE a separate living room. Consider how you want to use the space. Preferably, something other than "a pretty place for people to see when they walk in before they go to the family room." While that's fine if that's what you really want it to be, it has become the reason people are (unfortunately, in my view) eliminating "formal" living rooms in new homes. It's SO nice to have an away room, which this could be for you. So, conversation? Reading? Any musicians in your family? How about board games? In my house this would be the reading/conversation/music room, so I would furnish it with 4 comfy chairs in a circle with a center table, maybe a bookshelf or two and a piano. What you do with it depends on the space you have.