window coverings for modern residences.  

Honeycomb/cellular shades
These come close to disappearing when pulled all the way up. Plus, they look a bit like shoji screens when white and semi-transparent. Very nice diffused light. I have one on our sliding glass door (70") and that's about as wide as I would want to heft up and down. (Although you can get a motorized lift.) I think two across would look fine. Also, these shades have a higher R value than many window coverings, especially if you go with double or triple cell. I get the top down/bottom up mechanism for privacy, opening the bottom a little bit to let in air and opening the top to let in light. Love them.

Would love to see a photo...
Would love to see a photo...

agree
I am also planning on cellular top down bottom up shades for my windows also. It's a great way to let light in but maintain your privacy. I'd be curious at other window covering options people have. Below is a link to the images on google.
http://images.google.com/images?q=cellular%20shades%20modern&oe=utf-8&rl...

Ripplefold
Ripplefold drapes, using Kirsch's hardware, have a minimal stackback. These might be more in keeping with a modern, horizontal look, especially if your windows open side-to-side. See images here:
http://images.google.com/images?hl=en&q=ripplefold&gbv=2&aq=f&oq=&aqi=

Technadia
I love those! And yes, my windows can open side to side.
I am wondering with option will 'disappear' more. I want to be able to take advantage of the most window I can without too much being covered when it is open.....
I love the cellular too, but I think Technadia's option is the most aesthetically pleasing to me.

Nice discussion at the link...
Nice discussion at the link below. For what its worth, fan pleat drapes were/ are used in many MCM homes. Homespun fabrics has been making them for close to 60 years.
http://www.lottaliving.com/bb/viewtopic.php?t=5613&highlight=drapes

I would think
I would think the cellular would be the most minimal (short of buying polarizable glass) especially since the windows are not floor length, and are very horizontal. I would break the windows into 4 segments rather than just two big ones, this will allow you greater flexibility/control with the light.
I like the vintage look of the other drapes, but they seem to suit verticality more than horizontality.

I will have two sets of over...
I will have two sets of over sized glass sliding ... perhaps it would work well for that?And I could use the cellular for the horizontal windows?

Lucifer sum
I also like your idea of using 4 panels instead of two.... I could either do four 3 foot panels or 3 4 foot panels ... thoughts?

I used a mix of fan pleats...
I used a mix of fan pleats and solar/mecho shades in my house. They work nicely together.
http://www.mechoshade.com/

Mount inside the window frame
for ripplefold (or cellular). Here's old promo copy from Kirsch.

4
4 three foot panels. It's a nice manageable size, and will give you greater flexibility.

.
How about a paper folding screen in front of the windows?
I have a huge front window which gives no privacy at all so I took a very wide sheet of calico and stretched and tacked it like canvas all the way around the skirting of the window, it doesn't dissapear but does diffuse the light really nicely and the hideous car park across the road doesn't intrude. I think Rennie Mackintosh did something similar with muslin stretched over simple wood frames, if you google images of his white rooms you can see what it did to the quality of the light.
Or you could erect a lattice outside the house and grow a deciduos plant over it, nice shadows in summer and good light and still some privacy in winter.