What's the length you're trying to span? Are you thinking tension rod? Or attached to the wall above the door?

Rod would be attached to wall above door (rod pocket curtains). I don't have measurements with me at moment, maybe around 70 inches.

Sorry, not rod pocket. Curtains with grommets.

I've used wood closet dowling since it's a lot heavier and much more stable. Can't say if you would need a center bracket on a large slider, but if it were placed on the wall above the door, directly in the center, you could still slide the panels in either direction.

The width is not hard to find. Any adjustable rod would work with the center support. The center draw is fine, except I thought the curtains would be in the way going in and out of the door on the right. I talked to someone who wanted to do what I wanted. She had inserted a wooden dowel in one of the adjustable rods to reinforce it. Over time she said it had sagged and needed the center support. Don't know how big a diameter dowel she used.

I used this one, but since it wasn't the color I wanted I just put a coat of minwax poly on it. I hung the side brackets as close to the frame as possible but if your curtain is light you could probably place the brackets further from the frame if you need the room to stack the drapes.

To prevent sagging you need a rod (wood) that is at least 1 3/8" in diameter. Mine has been up for over 10 years and still no sagging.

annztoo, did you use the 8 ft. pole as is, or did you cut it any shorter?

I couldn't use the full length because one side wall has an angle. I ended up cutting off about 8" and just redrilled a hole for the finial.

If you need only 70 inches that same rod comes in a 6' length............

Think about hotel rooms. They so often have a room-width black-out curtain ... and behind it a thin sheer ... and usually some type of non-moveable header (either cloth or wood) ... and they pull open so nicely. While staying in a hotel a year or so ago, I decided that's exactly what I want, so I took a good look at the hardware involved.

Hotels have ceiling mounted tracks. Something like this:

This ceiling-mounted curtain track can be supported every 2-3 feet, eliminating any possibility of sagging rods as years go by. You can cut them to fit your dimensions, and they're even available in around-the-corner styles.

The negatives, of course, are that you'll need floor-to-ceiling curtains, and you'll probably have to do some sewing adjustments to the curtains yourself. Still, I'm going to do this in my bedroom, where I expect to open/close the drapes frequently.

I wouldn't do it in, say, the dining room, where I'm going to use plantation shutters and curtains that'll essentially never move.

annztoo, unfortunately, I need about 72". mrspete, great idea, but I already have the curtains I was hoping to use.

I have heavy, lined, pinch-pleat drapes hung from wood rings on 74" wood pole from Lowes (I bought a longer pole and cut it down) with no center support. No sagging so far!

zsmith, do you happen to know the diameter of your pole?

Long time lurker here :) I just ran into a situation like yours in our new home. We are remodeling and put in a window wall in the living room. Absolutely gorgeous, but I was not going to buy a $300+ curtain rod!! I used metal conduit and made the rod supports from the hardware section at Lowes. The conduit I used is 3/4". My short rods are 60 inches without a center support and the long rod is a 14 foot span- I used a center support there. The 60 inch is very sturdy, so I don't think 72" would be a problem! I saw the idea on Pinterest and it's a great way to have very long rods that look great without spending hundreds.

Arknewbie, it's about 1-1/2" diameter. I think Lowes' 8' poles are 24.97 to 29.97 depending on the finish you want.

In another room I used 1-1/2" closet pole bought from home depot. It's much cheaper than a finished curtain pole, but most of the unfinished closet poles in the lumber section are bowed.

We repurposed a 1.25" diameter closet rod to use over our 8' slider.

suzanne_sl, looks great!