I'd say for furniture you'd want something that is solid on the bottom --like a chest rather than a bench. But maybe Lil S' idea about a plant on a round thing (IDK mat/base) ... On the other hand, does that silder get used for something? Like, if it went out to the pool and you needed to keep a key or something there maybe a functional wall piece ---mirror and keys --not explaining well.

I think a couch that has less depth would work wonders in this space. You have a very narrow field to work with, albeit still doable. It might help to mount the TV, otherwise get a thinner console. Sectionals are usually unnecessary but if you plan to keep something similar, a sectional like this would work well. It has less bulk than your current couch and the sleek lines help to divide the room from the entrance.

@Roddy Reese I love! your sectional fabric. It looks so cuddly! I also am a big fan of chocolate color in decor. It goes well with a lot of my favorite colors: blue, purple, wine, red, teal… and sometimes colors I am not so crazy about like pumpkin. Can you share please what other colors you like? It will help people "shop" for you to show you ideas. I agree with @Sabrina Alfin Interiors that an area rug and something behind the sectional is a great start. May I ask if there is a large window or sliding glass door behind you as you photographed the sectional? If so it might be nice to have a mirror over the sectional…or not…art is always good, but I am not a fan of buying art for decorating. A mirror, however can have lots of uses over time. In this case it can reflect light into the room from the outside, assuming I guessed correctly. But maybe you would love a wall tapestry or weaving or sculpture. All I'm saying is maybe you would prefer something besides flat framed paper. ??? Then there is the matter of draperies or other window treatment. They could also be a way to bring in color. They also could just add texture if they are the same color as the walls. I see you have four pillows. You can stuff them as is inside decorative covers widely available and fairly inexpensive. Then if it's an option you can even choose a new wall color if you want. Your wall color coordinates nicely with the floor. Tying it all together will depend on the area rug etc. I am attaching some rug photos for your feedback so we can better under your style. I'm going with boho and your current colors for now, since you are trying to stay low cost and maybe even want a neutral color scheme.

@George S what do you need in your home? Storage space? Yoga space? Playroom? Kid camp-in place? What don't you have enough of in the rest of the house? Also, what are the environmental conditions there? Is the space heated, cooled, ventilated? Looks like there's a little heater in there? Can an adult stand up in the middle? Can a rowing machine for lengthwise? What are the key dimensions? Personally, I'd love to have storage space, because I have none…no basement, no article, and dinky closets. But you may already have more than you need. I have grown kids, and even my grandkids wouldn't be interested anymore. I would love exercise space but only if it's air-conditioned and ventilated.  For storage, you could put big things along the low walls or you could install shelving there and still have a little stool to sit on in the middle while you sort or search. I'm guessing this is a house new to you, and the previous occupants had kids? Or is this your kids' artwork?