Go to your local lighting showroom. The staff at most stores are trained to answer these questions. Take your plans and listen to their advice. They can explain lumens vs Watts, flood vs accent, and how best to light your space.

First, thank you for your kind words This is a very sweet old house and our goal is to do nothing to mess it up, for sure. We did a careful kitchen remodel before we moved in, mostly leveling the floor and ceiling and undoing some odd things that had been done over the years. We would be very careful with this as well and so I wanted to mine the depths of experience in the Houzz community. Our first grandchild, who will be two in July, has made us appreciate that being unable to see into the family room is more than a minor inconvenience. I believe that a thoughtful approach could produce a room that looks like it has always been more open. Taking the photo a little further to the right shows that the stairs are not an issue. The landing would not be affected. As you can see, a previous owner tried to make more of a connection between the rooms by adding a funny internal window. We don’t find it helpful, just odd. Other than the contractor needing to go under the kitchen floor to look for the proper footings and adding them if needed, I don’t think there would be a structural problem.

The glass doors do look nice, but, what is your objective for putting doors in this opening? Would you also add a door to the opening that leads to the kitchen in order to finish closing off the room? It seems that, at this point, you are somewhat unsure of what your intended purpose is for this room and what you want the doors to provide. That can make a lot of difference as to what you do to change it, if anything. The two options that you are considering are quite different from one another. Glass doors would neither give privacy to hide exercise equipment, or give privacy for an office of any sort. Do you need a home office for anything but personal business? If you had a home business where you received clients it might make sense to close that room off. But, you didn't indicate any such. Although the glass door are pretty, they don't really serve a real function of privacy, noise control, or keeping out toddlers. They would seem to serve more as a visual separation of space. Perhaps you need to first determine more fully what your objective is before you can make the best decision. Another consideration with adding doors is that it would change your habits of how you enter and leave your home. I will bet that you head right through that room into the kitchen many times. That is not a major obstacle, just a consideration. It would change the flow in your house. Either the doors would always be open, and quite possibly in the way, which would defeat the purpose of having doors. Or, you would need to establish a different pathway and enter your kitchen through another entrance. It think that you said you enter from the garage into this area. So, would it be true that you enter the house mostly from this entryway even when coming in from the car? Just some considerations. Whatever you do, one thing that I would strongly suggest is that you change the lighting fixture that is hanging from the ceiling. THAT is so "dining room, over the table"! And, there is no table. That little space could be used for many things. You said 12x12? That is not a big room. That is about the size of a table for six with enough room to scoot the chairs back. So, maybe consider just what it is that you are trying to achieve. Those types of door are like you might see on the entrance to a formal dining room where the table is staged and the doors provide a glimpse in and a grand opening to receive the guests. They have, traditionally, served some purpose of closing off a room from casual foot traffic while keeping the view. In times past, before central heating, many homes were heated room by room and the door offered some way to hold in the heat while preserving the view.

Condolences for your loss. Mother's Day is coming up. You might consider a digital picture display with a light colored frame with happy pictures loaded to add light and prompt happy memories.. https://www.google.com/search?q=electric+digital+photo+frame&client=firefox-b-1-d&source=univ&tbm=shop&tbo=u&sa=X&ved=2ahUKEwjd_b7llbnoAhXEmuAKHRT1DIgQsxh6BAgOECs&biw=1366&bih=654#spd=9152850867742305625 You might remove the too small rug altogether and add a small light/bright colored storage ottoman or even a coffee table where she can keep family photographs. Agree with the suggestion that you try swapping the loveseat and rocker locations. With the loveseat moved, you can dress the patio door/window. If that is a sliding door, a wood or metal rod in the bottom rail might make the room "feel" more secure -- no need to block it with a sofa. A lot of people don't care for vertical blinds but I consider them perfect for a patio door or even a large row of windows in an informal / contemporary room. White vinyl vertical blinds would provide more privacy and light control options than drapes. If your mom's window is on the north side of the building, she'll not be getting any sunlight directly into her room and that may be one reason why the room is "dark" . If any light comes in ... or even if it doesn't ... consider adding a brightly colored sun catcher or two that can be attached to the window via small plastic suction cup. https://www.google.com/search?q=tiffany+suncatchers&source=lnms&tbm=isch&sa=X&ved=2ahUKEwigr7T2k7noAhUvmuAKHahuBwcQ_AUoAnoECAsQBA&biw=1366&bih=628 There are fabric covers for sofas and love seats. Perhaps you could find a light colored one for at least one of her pieces. Alternately, a light colored afghan or throw might help. Instead of getting rid of the cabinet(s) in the corner(s), you could add a tall thin lamp with a large white shade there. If the big box store options are out of price range, check with Habitat for Humanity or Good Will or other local charity sponsored thrift stores for bargains.