How about something a little more rustic than sheers. Are wood blinds or bamboo shades an option? I think the brown sheers with the green curtains are going to look very dark, and perhaps dull.

Forgot to add that I applaud your efforts to make your home a warm and inviting environment!

I agree that the brown sheers will look odd....like they were in a smoker's room and not washed. I like bbstx's suggestion of wood blinds or bamboo ... I think that will look much nicer with the green drapes. I used bamboo roll up blinds in my craft room and they were very cost effective....

I love sheers! But mostly I love them because they shatter and soften the light. What would brown sheers do to the light in this room? Would they make the light murky? Or... maybe the effect would be dramatic and shadowy.

Do you get a lot of light in this room? Is there a view? Is privacy an issue? Must know the practicalities before we can discuss the aesthetics. Function before form!

Somebody hit me, please...

Sheers seem sort of feminine to me. I agree with other posters that suggest using shades of some kind or wooden blinds instead.

No, I definately want sheers, not blinds. I don't want to totally block off the view to my backyard. I just got rid of blinds. It's just a matter of what color sheers.
There are curtainless smaller windows up above these windows (high ceiling), so it'll never be all that murky. I'd rather it was murkier. I'm trying to bring the forest inside.
Privacy is not much of an issue.
In the daytime, the brown sheers wouldn't be very brown in any case, with sunlight coming through. But in the evening with no backlight, they will look brown, which would go with the rest of the room colorwise. I just don't know if it works on a window. I guess my main question is that I don't know if any color other than white is ever used for sheers that are behind drapes. Only time I've seen colored sheers, they were alone without being doubled up with drapes in front.

Well, not sure if this visual will help. but i did the opposite in my DR and I love it. Brown drapes with green sheers......

z(just ignore the mess in the rest o\f the room!)

If it has to be sheers, I wouldn't put a solid brown sheer under a solid green curtain. What you might do is look for a sheer with some pattern. This one from JCP would perhaps work, in either the sage or the brown colorway:

dorsset stripe sheer

If you go solid, then I would go for something more creamy, antique feeling for the hunt club feeling, and something with a shadow stripe or other texture, rather than the plain sheer fabric.

Do keep in mind that the sheers don't really fit the look you are going for, but if the light is important to you, and you can't just have the drapery open during the day, then they are likely the best solution.

Can you find sheers the same color a your green drapes? Or if you have to, a little lighter green. I see where you are going but I think the green/brown combination will be a little harsh.

Go to houzz.com and search on library. You'll find a lot of rooms like what I think you are looking for, and most have just heavy rich drapes without sheers.

This is one I found with sheers though not my favorite look. They are off white which is probably as dark as I would go.

But I would still prefer no sheers, especially if privacy is not an issue.

I think the woven wood blinds could work well in your room.

How about a sheer linen under the green? The link below is for a natural color linen. When you say "dark brown," I imagine something the color of a Hershey bar. I think the natural linen could be classified "brown" but not be as harsh as a chocolate brown.

If you already own the green curtains, can you post a picture of them? I did a Google image search for "dark sage green" and there were many disparate things with that label.

P.S. if you like the linen curtains from halfpricedrapes.com, sign up for their emails. They are always having sales! If you just wait a while, you can probably save some money on your purchase.

Here is a link that might be useful: sheer linen curtains

Just remember that the sheers will color the light that comes through the windows, and the altered light will color everything in the room, in the same way that transparent gels color theatrical lighting.

I think they will make your room look dirty and depressing, frankly.

Go with ivory, use a very sheer linen rather than the usual polyester gauze, and size them so that they are flat when they are pulled across the window. Otherwise, they look too girly for what you are after.

Unfortunately I've no way to get a pic up.
I think I misspoke when I described my goal as hunt-club.
I think more of what I'm looking for is more forest glade, with the leather aspect of the hunt club. I guess there's a bit of a difference.
Yes a natural fiber color might be a good idea as well. I have considered linen. Or even a natural color fine cheese cloth, or an unbleached muslin.

The green drapes are each like two panels, but joined at the top. So they will be tied back. Also there is a skirt (valance?) across the top thats about 12 tall with a bit of fringe. The material is a heavily wrinkled type.

I applaud your desire to create such a rich ambiance!

I googled "brown sheers" and found this, which might be similar to the effect you're seeking:

Supposedly these sheers have a subtle pattern, which might work for you.

Although I would want to see how they look at night.

Below is the page...

Here is a link that might be useful: Brown sheers

On the subject of fabric choice, I think you'll find that cheesecloth is not stable enough for a curtain, and that it will sag and droop.
Muslin is not translucent enough to be used as a sheer.
You could use cotton voile, however.
And there are sheer linen panels out there that have a subtle woven pattern of trees or leaves that might help reinforce your forest glade.
I'm still voting against brown, though.
Just think about how clear and bright a shaft of sunlight looks when it penetrates the tree canopy and shines on the forest floor...

You can certainly use colored sheers behind drapes. Look through JC Penney and you will see many, many combinations.

But it seems to me that what you really want is to darken the room a bit. I don't think the dark window treatments are going to accomplish that.

Beige walls and carpet and a white fireplace are not going to play well with your dark on dark window treatments. Since new paint is not an option, put some big stuff over that beige paint. You want to spread the dark/forest look around the whole room at eye level rather than going for a sudden blast of it on two small windows.

I don't know what is on your walls. But I think you could bring the outside in by choosing some woodland fabrics and using them to cover some large canvases. Or you can frame some large sections of wall with molding and either put fabric in the center or paint just that area.

I'm assuming you don't want to paint because you've got that big two story high room in a large open concept area...painting the whole thing is a big deal. So don't paint wall to wall, paint big sections that can be the background for any art you hang.