There is no window in the dining/playroom? If so, I think it would be fun to paint the back wall with chalkboard paint (any color you like - would not have to black), or use cork panels. With flat molding around it, it would look nice, and be frequently used by kids. It would also serve as a focal point. Alternatively, you could wallpaper the rear wall, or hang fabric panels as an accent. What is the room with the mirrored sliding doors? I have never been a fan of sliding doors - I would consider replacing with a pair of regular doors. If you like the mirrored aspect, you could have mirrored inserts in a panel door. Or with kids, maybe not.

Sophie Wheeler, my budget is between thrift store and Target! I love to thrift and am patient enough to wait until the right piece comes along. The only problem is that I don't know what that "right" piece is just yet! I am also a shameless IKEA fan. m_gabriel, thanks so much for the info and ideas! Painting is fairly flexible - it's a small enough space that painting it back to white wouldn't be a big deal, though the landlord showed me other properties where the previous tenants painted. I don't think they're too picky. I looked up a burnt yellow and that would be perfect for at least some decor/accessory ideas, and would create flow with other yellows/warm colours I have throughout my place. I was thinking of going with copper accessories, but I actually like the idea of sticking to silver for all metals then adding a pop of deep yellow for contrast and warmth. I don't host a ton; my boyfriend cooks with me and my book club is over occasionally. But I'm now wondering if I don't have a great dining space because I don't host, or I don't host because I don't have a great dining space. In other words, it may not hurt to create that area so it's more welcoming to guests. However, I'm very used to having very little dining space so it's not a complete loss if the dining area is used in other ways.

a few additional thoughts. consider moving and angling the two chairs a little away from each other so you can see the fireplace and put a low side table between the two chairs. you mentioned you like MCM, maybe consider swapping out the credenza that tv is on for a longer one that has more of a MCM feel. I would just get a large coffee table and not ottomans in front of chairs. curtains on windows will help soften the room. heres a few pics of mcm credenzas and a coffee tables with additional texture and interest. a photo gallery wall with bright colors might also look nice on the long wall.

Cool house! Oodles of potential! But you've got a lot going on here with the openness and adding a feature wall colour will not be doing the architecture any favours. I would keep it simple and go with one colour throughout. I would go with a white for the walls and the currently painted trimwork. Let the wood accents be the star of your house. That being said, there are 2 things that bother me in the photos. First, the dining room, why does it have a railing? Looks like a weird adult playpen. I would remove that railing and build wall-to-wall steps on each side of the dining room that go down to the lower levels and that would make your space more open and accessible. The other thing that bothers me is the very traditional furniture and lighting. I couldn't tell by your description if the furniture is yours or the previous owners. I would definitely replace all the lighting with something in a more contemporary style. Your furniture should also be simple lines and more minimal. You have an opportunity to make this a really special house. The architecture is already cool, what you do with it could make it awesomely cool!!