Ikea sells silvery wire-rod, which is for wall or ceiling. Spray it bronze or black...

They sell white fabric curtains too. Scissor and sew a couple horizontal strips in a neutral tone to create the height you need, an idea.

http://www.ikea.com/us/en/catalog/products/60075295/

A while ago, houzzers talked about using painters' drop cloths. Can own fabric be placed within these?http://www.ikea.com/us/en/catalog/products/80079363/

[https://www.houzz.com/discussions/need-help-finding-fabric-for-curtains-and-lining-furniture-dsvw-vd~2742950?n=2[(https://www.houzz.com/discussions/need-help-finding-fabric-for-curtains-and-lining-furniture-dsvw-vd~2742950?n=2)

You could drill hooks and place stationary grommet panels [with your own grommet placement] ... but that wood!

If you have ikea's sort of semi-sheers, these at sides in 50 x 120" enough? You could still use ikea's wire-rod with grommets I suppose.

Everdebz, thanks for the suggestions. I was looking at the Ikea curtain wire system but even that requires additional support brackets for spans over 55". That would be an option if I were to curtain the full height of the window but not if I were to only curtain from the second mullion down.

No one else is 'on' yet, but how artistic a look are you considering? I suppose you could hang something which would droop [but call it something better]. Use interesting ties.....

Lower option reminds me of townhome we lived in. Some in the neighborhood hung from patio-door height, and others hung from the above transom. Photoshop would be nice.

This is kinda what I was thinking in terms of the "lower" option.

In your loft you have a mix of this and that height, etc...? and the windows don't match height either.... no privacy needed at top....

Just a thought, but how about three sets side by side of top down/bottom up shades for a clean look that could fit inside the window frames. See this link as ONE option.
http://www.blindsgalore.com/products.asp?id=cellular-honeycomb/size-36x144/top-down-bottom-up/window-shades/

Brainstorming: You could perhaps screw a hook in the ceiling, attach a chain or rope that holds the rod up in the centre.
Or, how about making a folding screen.
Or, window film if you only need it for privacy. But that would block your view.

I like the second mullion down idea with sheers on the Ikea wire rod. Sheers may be lite enough not to droop. There are are magnetic hooks that might help solve a droop problem. I've bought incredibly strong magnets from Apex Magnets online. Your place looks like it would be fun to decorate!

Why not cover each square window with frosted window film...that way you always have light but always have privacy...

Very cool look and if you want softness from drapes you can do stationary panels on each side with hooks or short rods.

Idk about weight of curtains and drooping / 50 x 84 white and ivory with tie tops:

http://www.jcpenney.com/greta-tie-top-semi-sheer-panel/prod.jump?ppId=1c25991&searchTerm=tie+top+window+treatment&catId=SearchResults&_dyncharset=UTF-8&colorizedImg=0900631B81C66CDBM.tif

Just trying - if you had 84" lightweight, what about this from pipe topmost, hanging to cover the wire...Would 3 look 'put together' enough? It might.

http://www.jcpenney.com/weathermate-room-darkening-grommet-top-tie-up-curtain-panel/prod.jump?ppId=pp5004860360&searchTerm=tie+top+window+treatment&catId=SearchResults&_dyncharset=UTF-8&colorizedImg=DP1111201417013820M.tif

Tablecloths often come in long lengths and are unbelivably inexpensive. You could hang them with drapery clips. http://www.cvlinens.com/90x156-rectangular-oblong-polyester-tablecloth-black-p-622.html

Hey There: I am following this discussion about your window treatment - talking about inexpensive can be anything. Looking at your loft window, you will need curtains that you love and suit the place best. I love the idea with the piping rod a lot and getting fabrics for it shouldn't be that expensive. What I want to advise you: don't go cheap - go froogle. Good Luck