I would paint the wall too! Nice ad bright!!

any gas log fireplace should have very specific instructions for safe installation with measurements for distance from back and side walls, height above floor and height of any mantlepiece above the front of the heater and details of the correct method to enclose the flue..first check these instructions and then decorative finishes will be much easier to decide...if you haven't chosen your heater yet all the instructions should be available on line and this will also help decide the best heater for the space available

To me , I'd want to know the style and era of the house , and the look of the other rooms , and even the size of the room . On it's own , with that art , and white walls and timber floor , I'd say do a white leather suite ( or 5 or 6 matching white leather chairs ) and a large screen TV on another wall , and a large coffee table in either white gloss , or black frame and smoke glass top . And then set it off with 3 or 4 green leafy potplants ( all different plants and different heights ) in pots in similar blue and green and mustard hues as the art . Any windows do in light wooden ventians ( white slats would be overkill without seeing the room IMO ) or black as a contrast . Add a mustard or jute rug . BUT that may not suit the rest of the house , or the size or shape of the room .

French moulding was used to add interest to large walls by creating shadow and shape. Plenty of Paris and New York buildings only have key walls done or key areas such as foyers. If you follow the guides of “place” and “proportion” you should be fine. Place meaning a sense of appropriateness ie a flat roof mid century house is not the place for French moulding and Proportion meaning working within the rooms physical shape ie hard to get a real impact in a low roofed small room. But as always have what you love.