We have two sliders on either side of our kitchen in this FL house that have no window coverings--
vertical blinds were there when we bought the house and we hated them--
had them taken down when house was painted so the holes could be covered.
But I want some drapes to give us some privacy mainly when we are not here...
We have covered lanai so sunlight coming in is not so much an issue--
My husband thinks if we have grommet top drapes on a rod that we will need a support hook in the middle which will prevent drapes from sliding all the way back...he is wanting to go back to vertical blinds (ugh>>)

One door is about 76" wide--doors recess into wall but we normally open on one side...two 50" panels would work
The other doorway is longer--more like 105 or 106...would take 3 there
so far we use the other door lot more for going in and out to lanai

How wide does a curtain run/rod need to be to need a center support?
Would using heavy duty anchors on the rod make a big difference to carry the weight...
I know of material weight and number of panels would make a difference--

these will be 84" long--looking for something that is casual, like a linen or burlap type material--but that does offer some privacy...
Saw some at JCP site that might work but haven't checked stores yet to see if I like the material--they have nickel grommets which are more difficult to find--
Our local Penney's might not even have in stock...

I have also seen some bamboo type grommet slider panels which I like but think they might not be that easy to move back and forth...

Here is a link that might be useful: Patio panels at JCP