Here's a pic of my dining room that Sheila is referring to. Obviously if you're already my friend on Facebook you've seen these pics but surely we have more readers than just our Facebook friends, right? :)
My husband has made an observation about me and it's that I seem to like to be bold with my wall color and then just keep it neutral with my accessories and furniture. When I look around our home I see that he's completely right. Isn't that the exact opposite of what they tell you to do? You're supposed to keep it neutral on the wall and use bold accessories. Whatever blows your skirt up, I guess.
So anyway back to your foyer. I love the dark gray color. How about jazzing it up a little with a stripe or stencil? It'd be super easy since it's such a small space and it would have a big impact if you did a really wide stripe or x-large stencil. I don't know what the finish of the paint is (eggshell, flat, satin, etc.) but you could get a clear gloss and use that as your "color" for the stencil/stripe and it would give it a nice monochromatic look.
I love how the new color and the natural wood tone of the doors (I'm totally jealous of the non-painted doors, by the way) ties into the mosaic ceramic tile. What about a nice bold rug?
They're all from Ikea but you get the idea. Maybe a fern over in the corner and one of those DIY sunburst mirror's that are all over the world wide interweb on the wall across from the door. You'd be in business.
Now as for the chair and the slipcover. At first when I saw the chair I thought "Oh, yay. She can try to paint it like that one I saw on Young House Love." (They actually borrowed the tutorial from here.) But then I looked a little closer and it seemed like there might be some damage to the original upholstery so I figured you'd be taking the train to Slipcover Station.
I love the drop cloth idea. My curtains in the dining room are painters drop cloths and they didn't require any sewing at all. One suggestion I'll give for making a slip cover fit like a glove is to put it on the chair while damp rather than completely dry. That way you can stretch it around the curves and as it dries it will hug them a little tighter and look more custom. Can you please please please do a little ruffled skirt on the bottom? Or try the freezer paper stencil? Or use grommets so you can lace the back up like a corset? Or even dye it a fun color? Olive green, perhaps? ;)