First "widen" the appearance of the window and consider alternate placement for the parts of the sectional before considering art for the walls. Any changes to the window treatments should be done before choosing what you put on your wall. You don't need to limit wall decor to framed pictures. Shelving -- floating shelves, box shelves, corner shelves -- can hold family treasures. Pressed metal art and other wall hangings can be used. Like your tables and lamps but the lamps could use larger white straight-sided lamp shades. Any change in placement and lamp shade size you and any additions you might be considering would need to be done before you decide what to put on the walls. DO move the sofa away from the exterior wall so your window treatment is not pushed/squished against the wall behind it. Also, be careful to not have them dragging on the floor (something which can contribute to that trapped/squished appearance -- drapes should drape). You could change your curtain rod to a double rod and put the lighter colored panels on the inner rod if your lighter drape panels are actually sheers which you can keep closed/together. Your window will appear larger and better sized for the width of wall if you use a double rod wider so you're drape panels will be covering wall and frame but not window glass. If the overhead light base can hold a ceiling fan with light, do consider one for this room. Lighting could impact what you decide to put on the walls. See if you could find some bolsters for use as arm rests for the different parts of the sectional. No one really likes sitting for an extended time without arm rests -- whether or not you separate the parts of the sectional. Do at least experiment a bit with dividing that sectional sofa into its different sections to enable you to set a plant stand or floor lamp or table with lamp -- something other than the huge sofa (which blocks part of the light -- in front of the window. See if you can put the two longest sections facing each other and put the two chairs on each side of the window, perhaps with a floor lamp/table combo between them in front of the window, so you can keep the two tables and lamps you have on each side of the room at one end of each longer part of the sectional. https://www.antiquefarmhouse.com/rustic-table-floor-lamp.html?gclid=EAIaIQobChMIr8uB4YSR5gIVJeeGCh0LZwBNEAQYBSABEgLGH_D_BwE

Can't make a drawing but like what you did. I like the chairs and the little table and lamp placed like your last picture.. Is the chest you moved to where the fan was, tall enough for your TV? If not could you hang the TV on the wall? The little chest looks out of place shoved up against the dresser with no purpose. Centered in that space might be better. No, I think your rug in front of the fireplace is good. Other than that, how would it look at the foot of your bed between the bed and dresser? I

Thanks for everyone’s advice. I recommended reupholstering the chairs with modern fabric. Compromise is that SIL will get slipcovers instead as this reupholster was expensive. (This is for future when she and my brother downsize to move to this house.) I moved one of the non-matching dining chairs to the bedroom. I like the dining chairs after seeing them in person and the seat covers are pretty. To protect them, SIL added temporary slipcovers to the seats of all the dining chairs. I am still searching for alternative covers but lower priority. Here is an update with the counter stools which I chose because the room is dark, layer another modern element, and they can be wiped down. Our next trip we will bring the standing lamp from the bedroom for the dark corner behind the desk and knockoff Eileen Gray round adjustable table for between the chairs. The room, whole house, has great overhead lighting and could use ambient lighting.

If you are at all DIY inclined, a box shelf -- or a pair of them -- on the wall just above where a headboard would be, with or without any kind of door, could provide a place for eyeglasses, clock, radio, cell phone and a pair of clamp lights or small lamps. https://www.lampsplus.com/products/black-adjustable-gooseneck-arm-headboard-clip-lamp__74412.html You can make the inside shelf space taller the height you need for what you need to set in it. https://www.wayfair.com/furniture/pdp/wrought-studio-keiper-solid-wood-floating-tv-stand-for-tvs-up-to-70-w000729469.html You could use painted plywood and shelving boards (6"-8" wide) to create a headboard with storage behind it. https://www.idealhome.co.uk/bedroom/small-bedroom-ideas-194262  Then you could focus on a good chest of drawers or two. Budget permitting A pair of wall sconces could hung on the wall beside the head of the bed where you'd usually reach for a lamp atop a nightstand. (A box shelf could be hung on the wall beneath them.) https://www.lampsplus.com/sfp/1M557/?cm_mmc=GOO-SH--NA--NA-_-1M557&sourceid=DFGPD1M557&gclid=EAIaIQobChMIwaCQnZzx6QIVCY3ICh1hFADiEAQYASABEgI3X_D_BwE Relatively inexpensive square foot lockers can provide storage and could double as a bed side table as well. If you want a glass top for square footlockers, check the thrift stores -- Habitat for Humanity Restore stores and Good Will usually have round microwave and square glass oven trays in different sizes -- but make sure what you get will sit level and not wobble when set on a flat surface -- unless you're inclined to glue "feet " of some kind to the bottom of it. .