So a transitional sofa in a light neutral color flanked by end tables/lamps to the right of the fireplace, a media cabinet under the tv flanked by two substantial but lighter chairs or recliners, and painting the fireplace surround to match the trim or strip/re-stain it to match the floor will lighten and brighten the space. The Roman shades in the dining area are the only window treatments needed…the whole space would benefit from a cohesive design of light to medium neutrals/color with some interesting textures rather than competing bold patterns. I’d change the lampshade or bulb so the small console lamp does not shine yellow.

I agree with most of what Susan said. I would also consider painting the walls a lighter neutral color. Is the fireplace surround stone ? If it is, you don't want to paint that. I would definitely paint the mantel white to match the rest of the trim, though. I totally agree about removing the curtains. If you still want curtains, then consider replacing them with textured, neutral colored curtains in a solid color.

By fireplace surround, I meant the wood mantle/trim surrounding the fireplace, not the tile. Thank you for pointing that out!

I'm not going into all the details, just an overall view. You have a lot going on in your living/dining area and the walls seem quite dark. I would suggest you paint the wall in a lighter colour, perhaps get a wall unit (on the wall you presently have your TV) flanked with 2 comfortable chairs. You seem to presently have a beige area rug in your living room that perhaps can be moved to the dining room to tame down all the different chairs and colours in that area. Sofa in the beige/greige tones with area rug (muted tones) and accent pillows to tie in with what you have in the dining room. For more impact, less small objects on your matel. Have a look at the visual that gives you an idea...

IMO the walls are too dark. It's hard to tell the color but it doesn't complement your cabinets as I see it from your pictures. Your kitchen is not transitional. The mosaic backsplash is busy. The DR curtains don't really complement the rug so They could be removed so the lovely roman shades stand out. Remove the clock from over the mantle and replace with art. A sofa and 2 chairs would look good. And agree with painting the FP mantle and surround white to match all the other trim. Paint color is best chosen after the furniture. Look at BM Gray Wisp (as suggested by the Pros on here) for all the walls. Open concept should have all walls the same color.