It's such a pretty room already, you just need to add the icing. I agree with those who suggest moving the couch to face the fireplace and put 2 chairs facing each other between the couch and fireplace with the coffee table in the center. I'd also chose the slipper chairs because of their scale, but they may not be the preferred TV watching chairs for your family. How much room is there from the end of the couch where it is now and the wall facing/opposite the fireplace, behind the camera? If there is enough room, you could add a sofa table with a lamp or lamps on it behind the sofa (in the new suggested arrangement. That would bring some light to the middle of the room. ETA: I reread that you are replacing the armchairs. That opens up the options so much. I'd find a style you like and then search for that style made in a fabric you love, or have them custom made with your fabric, if that's in the budget. I don't think you can go wrong if you pick something you love, but if you are unsure, post choices here for opinions. These may not be your taste, but may help you start thinking about what you would like: Maybe not blue, but an all over print:

Have you considered pulling your furniture away from the walls? I know that is not going to make it brighter but just something I noticed. I too think a rug would look great and lighten the space with some color. Try a polypropylene rug. We have pets and ours hold up well. I have a friend with 4 kids and her rugs always look nice. Just make sure to clean up spills when they happen. Esale rugs has many to choose from and great prices along with free shipping. I would add some lamps next to the couch and maybe try another floor lamp next to the chair... or you could find a small side table and place a lamp on it. Lamps are very important for ambiance lighting. Rooms look more bright and balanced when you have a lighting source that is not just from overhead. You have a lovely space and I am sure with a few changes you can brighten it up!

for sure paint the ceiling white. just use the white base straight out of the can. don't have it tinted! use a flat, ceiling white. painting the ceiling will have a huge impact on the reflective quality. if doing white on the walls, it's really going to make the trim look dingy. I'd redo all the trim (do a little at a time) and the ceiling, and reevaluate the wall color. if you still think it's too dark, try BM Pale Oak

We used to have a rug in the living room but we have three dogs and there was one where she would like to take her afternoon break on it somehow. We removed it and then she stopped her afternoon pee breaks. Perhaps i can try it again and see if she will do it again. and since I have three dogs, the other dogs follow suit.. :( I don't have a dining room; only a eat in with the kitchen. I do however, have a small area in the kitchen for a changing table. and we are planning on using cloth diaper so it'll be interesting lol. Unfortunately, I don't think I have option to create a pass through wall. The only wall I was thinking of being able to knocking down or creating an opening is the one that leads into the kitchen but there's an air vent at the bottom and light switch on the other side of the wall :( Preferably I'd like to keep the bench as it has four big deep draws. I can probably put baby stuff in there without having them lie in open areas of the house. My original thought was using the corner space with the window for the baby area as it does have some light. I bought Ikea frames kind of matching to the bench and was going to hang two above and I also have a 2x4 foam core picture that I'd like to hang but if it doesn't match then I probably shouldn't use it...(see picture below) I was also looking at Montessori Toy Storage based on other Houzz member suggestions and placing foam mattress for the baby. The wall paint in the Foyer and living room is Benjamin Moore Cloud White. The paint in the kitchen is Benjamin Moore Lemon Sorbet. I don't think we will be repainting the walls. I'm hoping to keep the budget within a minimum of course now that we have a baby coming :). Sofa is really the big furniture I was thinking of replacing and may be the hanging lights. Wall that I was thinking of putting an opening through but there's a vent at the very bottom behind the recliner and there's light switch on the other side of the wall in the kitchen. I was thinking I can put the changing station in this area with a change pad over the existing ikea cart. the hanging light with reflection The bench area where I bought the Ikea frames to hang around. The hanging light with reflection in the ceiling May be I can reuse this wall tapestry for the sofa but not sure if it's too light and need a darker version.