Rather than focus on the wall of windows you might first paint the walls a mid-tone or darker which will do wonders at warming up the room. You may not then need to dress the windows at all. You have very valid reasons for leaving them uncovered. Window coverings for that expanse of windows will be very costly and there are many other ways of warming up the room. If you are interested in having plants to soften the space you might consider a couple of Dieffenbachia as they are fairly inexpensive when small and grow quite quickly. Of course there are warnings about the toxicity but I've never had kids or pets eat them and I have read that warning is over-rated. I've had one grow to over 8' tall and seen them much taller than that. They actually do better in lower light situations and mine did well in a north-east window. Whatever plant you choose you could put it on a pedestal when small for greater impact. I'm not a fan of accent walls so wouldn't advise painting the fireplace wall a different color. Too often accent walls don't work as intended for interest and I think there is enough going on in this large room so that keeping all walls the same color would be best.

You know, if you wanted to do "in ground", you could make a raised bed inside that spot... bet a bunch of bricks againts the house for a raised bed... that way... they get to be in the ground from the start... I mean, if you don't plan to move those evergreens in front then you can bring anything back there to help you... if you do make a raised bed there, I would probably go with a couple of bushes of roses to cover that entirely area, do your research first... there is a lot of info in the "roses" part, like what kind of color, zone, how big, and you definitely want a repeat bloomer and BS resistance.. That is Black Spot btw ;)

A piece of furniture- console, buffet, etc. and art above. It’s not a boring spot. I’m sure you know this but art doesn’t have to cost a fortune. Actually I recommend against it. My most expensive piece of art is in my attic. I can’t bring myself to get rid of it quite yet. My most enjoyed pieces are from second hand stores, originals, and very inexpensive. Favorite one is a large framed oil pastel that was $4.

Yeah, you're sort of screwed by the doorway to the dining room -- there's no real way to set up the door side of the room as more than a sliver by the windows. You're on the right track in treating it as two separate zones, though. Here are a couple ideas that might help you visualize the right solution for your family. 1) Treat the area near the door as a Kid Containment Zone. Put a bench where the entry table is, with baskets underneath for shoes, and maybe a couple of hooks for (future?) book bags and so forth. Then put a small table right next to the door, in front of the sidelight, as your entry table, with a bowl for keys or mail or whatever (and a drawer for mittens). Reading chair and lamp in corner by dining room, to look inviting for a pause, might never get used, or could have a small bookcase for kids when they need a moment to themselves. 2) Make that zone a gaming area, with a smaller table against the windows and 2-3 chairs. Floor lamp in corner for evening activities. A puzzle could live there, or it could be the go-to space for games. Or you could instead do a lower crafts table and a storage cabinet. (You might have those kinds of spaces elsewhere in the house.) 3) No matter what you do with that zone, I'd enlarge the living area in both dimensions. Couch against the wall with chairs on kitchen side, table and lamp between chairs, large coffee table (think a big circle!) that can double as together-activities zone. Use a big area rug to anchor and define this area, and let it come down very close to the hallway to the bedrooms. This will help you scale your furniture and help eat into the dead zone. If you entertain, you might add another arm chair on the doorway side of the ensemble, or use an L-shaped couch, to encompass more seating and enclose more space. HOpe this helps!