If the tv has to stay above the fireplace, you have to get the wire situation taken care of. Get the electrical and cable moved so it's behind the tv. I feel like to balance out the dark floor and brown sectional, I would paint your mantel dark. I would flank it with two media cabinets to which you can add baskets for toy storage and house books and DVDs. Consider a long narrow storage ottoman. You may be able to get some larger toys in there. Flooring-I recommend carpet tile (flor.com). With kids and pets, you can just pop a tile out, rinse it off and put back. Lighter background. I would extend your curtain so drapery panel just fill the wall space on either side. Art above the media cabinets and above the sofa something three dimensional like metal art, metal letters that light up, etc. just not a mirror. And it looks like you may have room for one maybe two accent chairs. The board is just conceptual not necessarily a color scheme.