I'm thinking maybe an open tall bookcase that you could accessorize and hold reading materials that you'd use at your swivel chairs? That would cozy up that corner.
May I ask what color that great blue paint is?

I think you have 2 options.

2 large armoires that flank he fireplace or screen to the right of the fireplace and a seating group to the left of the fireplace.

I have a blog post that may help you out.

http://www.timothyriversinteriors.com/blog/

What is the length of the TV wall? A long shelf under the TV to hold components, baskets, artwork, would help fill the space to either side. Depending on the length, you can get two or more console tables, and place them end to end to span the space. There are many DIY IKEA hacks of their kitchen cabinets to make a floating console of the desired width, you can use any brand, or salvaged. Once you have a "base", you can add art to the walls, either a gallery wall, or just one big piece.

I'd build a bench under the window. Great spot to soak up some rays and enjoy what I assume is the lake view. A piece of art on the wall similar in size and mood to the one in your dining room.

I would put some fun wallpaper on the tv wall and do a ladder on the wall to hold blankets.

Wallpaper Idea

A bookshelf or large floating shelves would look great. It's a nice space and the wall color looks great with the floors.

Just curious, where did you get the art in the dining room? I've been looking for something similar. Thanks!

Take a photograph of the lake view and blow it up and have it mounted on canvas and fill the wall with it. There are online companies that can make a photo in any finish and size.

If you enjoy the built-in look consider going for a leaning bookcase or etagere. We chose three unique styles that we think you might really enjoy. This Monarch Specialties Bookcase is stunning but might also be a bit small so we also chose an 'X' Bookshelf and a Open Concept Display that are larger and would fill up the space more. Let us know what you think and if you need more product recommendations or tips!