One shutter per window is my vote, or else they would be way too skinny.

I agree. One shutter per window, otherwise they would be too narrow. Plus a pair would block even more of the natural light from coming in.

Barbara, that is what I have on my windows. The perfect solution as you are able to open the top/bottom separately. Best investment as you can add fabric panels if you choose.

Thanks everyone, we really appreciate it!!

Barbara, do you think we could pull off 4 1/2 louvres?

Why use the hidden tilt bar, then add a divider rail? Use the hidden tilt bar, but use a cut hidden tilt bar for the same function.

+1 to one shutter per window

Yes Josh you certainly can do 4-1/2". I have these shutters in my house. To "The Shutter Co.", I will always use a divider rail if the window has 2 parts, otherwise you can always see the window divide when they are open and it just does not look right. It also gives a lot more stability to a tall window. It also looks better if you open the top and not the bottom. I have seen the split tilt bar and do not like the look of it when used to open only a portion.