With a wall like that, I'd go with floor-to-ceiling bookshelves with a mezzanine level! But...maybe that's a bit much. If you want to add bookshelves but not interfere with the stairs, you could move the landing out one step width, there by raising the landing by one step level, and then extend the bottom-most step out into the living space.

@incubus_of_habit do you have any photos of what your talking about?

What do you need to store in a living room???

@scottsh1 I was thinking something like this (If budget allows):

HI -- That is a massive wall to deal with . First thing is that fireplace looks so tiny for the wall . I think that mantel surround needs to be replaced with something with more height and presence . Unless you have lots of books I would not over do book cases .Doing the whole full wall with shelves and or bookcases is overkill . And who's going to climb that high to get a book and who's going to do that to dust either. I like the bookcases that Restoration Hardware has,-- but don't put too close to the stairs . I think you could add a grid of boards for some texture on the wall to make it more interesting than it just being flat . Or maybe a wallpaper that looks like concrete or brick or old wood or even a photo mural . Search on Houzz for feature walls and tall (modern?) fireplaces .

It isn't a great focal area since the traffic and stairs interfere with grouping furniture there. Have you a better wall for the FP and built-ins?

You could make your fireplace larger visually by adding to the base with stone or a larger wood surround and then extending the fireplace wall up to the ceiling......Then you could build in cabinetry on the right side since the stair is in the way on the left.

I have found a few photos of fireplaces with cabinetry that might help you with your own design.

Another option, after extending the fireplace up the wall is to place a beautiful tall cabinet on the wall to the right and then add a large painting above that........

Most photos that are out there are symmetrical, but you can have a one sided fireplace cabinet that will look good..... I couldn't find any photos.
If you draw the elevation of the wall and do some sketches you should be able to get the proportions right.......Or you could hire a local designer to help....

is there going to be a tv added to the wall here?