Sounds quite pretty to me, with all your darker color in the room. You didn't mention any furniture color, so I'm assuming you may not have it picked out yet. I usually choose to paint most of my walls in a soft cream color. That gives me options when it comes to changing color in the room. If your a green lover, I would choose a soft, light sage or moss on the walls. If your not, you can basically use any color you like, as long as it doesn't clash with your rust. Rust is a neutral color. So is the brick on your fireplace. And hardwood floors are the best. Depending on what your favorite colors are, you could use almost anything; even blues, either light tones or dark, if you want to stay on the dark side. I also like using Taupe. Possibly a medium shade of it as another neutral. If you like bolder color, you may want to try deep plum, or gold. A combination of these would like nice too, depending on your furniture color.If you like bright color, maybe a yellow ? I wouldn't use red, since it would clash with the rust, in my opinion. Gray would be too dull too. I have a lot of rust in my home & I use a lot of taupe, gold & purple tones with it. If you like a Southwest look, aqua or corral would work with the rust. I also use some of these colors in my accessories like curtains or pillows. Even bring in some black. Good Luck decorating & have fun !!