Get a rug that is 2-4 feet wider than the sofa. Use painter's tape and tape it out on the floor. The taped "rug" should slip under the front 1/3 of the sofa and extend past the ends by a foot or so. If you get a leggy chair, it should sit entirely on the rug. I advise a larger, visually weighty coffee table to work with the sofa. The one you have now is just to spindly and feminine for the seating pieces. It should sit 18" or less from the sofa. Once you have the table, pull the other seating pieces to within 18" of it for conversation and putting down drinks. Otherwise, they'll need their own side tables. I'm guessing you could use more lighting.

There are many problems here, but I'll only focus on the biggest ones. Yes, you need an area rug. You need a larger coffee table. You need throw pillows that aren't white (get the warm colors from the art work). Remove the odd stand in the corner. Remove the squiggly piece of art work. Remove the curtain panels. Replace the mirror in the dining room with art work pieces.

Same dog, different rugs:

Emely, I don't know about rules, but now that I look more closely, I should have ruled out the third rug because the pattern is too much like the pattern in the canvas. It sounds like you might prefer something more neutral, maybe something with more texture than pattern.

Let me see what else I can find.

Emely, the first four rugs are from Crate & Barrel, fifth rug is from West Elm, last rug from cb2.