Prefer either the gray or the color left of the gray for decking. If at all possible, keep the deck one level. Decide on your deck color before deciding on any color for the art frames. Is a rectangle the only option for shape? Could you wrap your deck around a corner so you have sun/shade option?

Please ignore the 'pro' debby downer, who can't seem to say anything positive about anything. IMO! Will the paneling be vertical or horizontal? I really like the stone to the ceiling in your rendering. If you imagine what will go above the mantel (no tv but likely you will need large artwork because of the scale), if you stop the stone and do paneling above the mantel, then add art on that, you'll get a bit of a chopped up look - 3 materials (stone, wood, art) instead of just 2 (stone, art). I also think it will look nice from the upper floor to have the stone all the way up. If you hang art above the mantel, I don't think the tall stone look as imposing; above the painting will not be dominating, as your eyes will focus on the art and the fire. I've been looking for inspiration pics with cedar paneling and stone fireplaces on a vaulted wall, but they are hard to find.

IMO take the TV off the FP and hang it on the wall above the blue credenza then think about wall color # mismatche dchairs are at least 2 too many . At least you had actual stuff that is nie to display on the shelves so good on you. I think a new rug and take the chairs awy for now get the new rug then decid which 2 chairs you want in the space any chance of getting a matching chir to the one by the credenza, Then a nice a bit more colorful rug withsome blue in it and some other color to use for accent like yellow maybe . Wall color after thi=ose changes are made could be just a nice white that works with the new sofa

Without the measurements that a pro would know to provide, there is no possible offering of a solution. That a pro would not need offered. I suggest you contact an actual design pro to do an as built for the space, and then use their services to space plan what is a very expensive project.