I'd love to see a photo of what you're up to, but it sounds like a thicker curtain would work well in your space. I'm not a fan of gauzy light curtains anyway, but with your strong furniture it sounds like they'd get lost. Your color combo sounds great - love the creamy grey chalk color with the turquoise and yellow. I thought this pic might help you with inspiration for the space. (again, would love to see the room to know what you're working with) I like how this designer combined all of the patterns and colors here - a great example for inspiration for you. Best of luck!

[eclectic home office design[(https://www.houzz.com/photos/eclectic-home-office-ideas-phbr1-bp~t_732~s_2104) by los angeles interior designer Vanessa De Vargas

Here is a link that might be useful: Inspiration for you

Egads! Don't limit yourself, my friend! Depending on the overall style of the room, you have myriad options! Not just for the window treatments, but for softening all that hardwood and making the most of your natural light! As for the off-center fireplace and abutting windows; you have the opportunity for some seriously dramatic style there!
I absolutely adore the fabric for your Smith Bros. chairs! Lacking actual pics and not knowing the wall color makes this a little more challenging; but I've based my suggestions on the information given.
First, let's address all those windows...
*Don't be afraid of lightweight fabrics; semi-sheers can have enough substance to hold their own against all that hardwood and color without detracting from the contemporary style of your chairs or your natural light. Think texture and natural fibers: linen, dupioni silk, tussah silk, and (my choice) handwoven silk. The first three have wonderful nubby textures, tussah has a fantastic texture of it's own, and handwoven silk has a strie pattern and texture that is stunning! All have beautiful drape and play with light, giving substance and visual impact to your windows.
*Go contemporary with a nod to tradition: Use straight panel clip top drapes suspended from a simple rod via rings and breaking an inch and a half on the floor. Layer these over similarly textured sheers about two shades lighter than the primary drapery color. I suggest staying in that light brown range as in the fabric on your chairs, then bringing in a splash of turquoise or green with banding. (Note: Top-banding gives the feel of a valance without losing the simple, tailored elegance of the drapes.)
*To give the illusion of height on your windows, hang them as high as possible. If I were doing the design, I'd have them hanging from simply styled bars suspended from the ceiling.
*Tone-on-tone fabrics and wide striped silk (no more than two colors!) are good ideas as well.

*Don't forget area rugs to define spaces within the room and to ground and soften the design.

*Place a large mirror over the fireplace to maximize the natural light coming from your window wall! Lucite, glass, and resin reflect light as well...

Good luck! Feel free to contact me if I can be of any help!

Live Beautiful!
~Juliet

Here is a link that might be useful: Dream. Style. Home.

Hi, Jeannie! I thought this might be more useful to you- it's an expanded response with images.
Live Beautiful!
~Juliet

Here is a link that might be useful: Window Treatments