Consider leaving the walls as they are and put the money into an art collection. You can rotate art seasonally or when you want a change.

Ebony, what a lovely space! This architecture is a bit more traditional than I would suggest an accent wall for - what you might enjoy is taking the dining space to deep shade up front and letting the light work for you back here. Right now, the only reason to keep this pale buff tone is if you have lots of terrific art on large canvases. That is what I would look for first, in fact. The other thing you can do for "art" since you have gray and purple accents is to print a lot of your own casual photos cropped in close in black and white and have the local copy place print them as large as possible without pixelizing them. Matt them all in white with black frames and make a gallery on the end stair wall.

One of the tricks of a two story space is making it feel comfortable to sit in

There are some beautiful warm grays with purple undertones - taupes, really, that should work well with the other elements here - but they all depend on what color gray your gray is. Some grays are true grays - almost read blue when they gather certain light. Some are platinum / warm grays and some have a green or blue-green undertone. Yours are most likely to be in the platinum or warm gray family if you have them mixed with purple.

Test ben moore's portland gray against your sofa tone - http://www.benjaminmoore.com/en-us/paint-color/portlandgray but stick with the same color everywhere except that from room - it gives the house a nice flow. Here's a fun deep color for your front "formal dining room" ben moore's tulsa twilight. try it in high gloss beneath the wainscot and use the portland gray above. If you want an accent in the space, instead of a wall, do the inside of the front door in that same gorgeous twilight tone. . . add some geranium pink and white for summer, and mossy greens for winter in accent pillows and kitchen linens.

With the color scheme and these paints, I'd look at west elm for some of their lucious ivory velvet drapery and generally add in more cream and gray, then focus on art. Art with pink, blue-purples, grays, blue-greens, violets, plums, . .. . a little purple furniture goes a long way.

This is actually the furniture I'm looking to place in the home

Ebony - those are great violet tones. If you haven't bought the set, loveseat and sofa combos are notoriously difficult to lay out. You might rather have more chairs than a loveseat - they actually seat more people. Great tall chair if it is comfortable - that is critical for a good reading chair by the fire.

Agree. I was actually looking at purchasing two chairs instead of the love seat

In a living room with fireplace usually focal point is fireplace and the wall is accent wall.
Depends on gray shade of furniture, choose the wall color. I assume it is cold gray and purple so we need something warm on wall like Cathedral Gray (Benjamin Moore SCP-205)
You definitely need to cover the windows on that wall I suggest Silhouette shade (Hunter Douglas) with motorized control system in neutral color. Complete your design with an unique elegant decorative mirror.

That is a great space and I agree with Shiraz Design, the focal point is usually the fireplace.