I am biased as I love California shutters, they are 3.5 inches vs the 2.5 plantation shutters. We just had the entire house replaced with shutters. If you are thinking cost wise, especially since you have a round transom, draperies will probably be cheaper as anything custom in shutters is $$$$. I dont know which is more energy efficient, but shutters would give you more options as to how much or little sun you want in the room, more in winter, less in summer. Shutters are the only window treatment to increase the value of the home is what I have read.

I'm comparing apples to oranges here - having had lined draperies in our previous 75 year old (minimally insulated) home to the 4" wood plantation shutters that we have in our new energy efficient home. But I will say that I love the shutters so much more than the drapes! We had them installed on every window in the house (except for two glass block windows) and while it was a significant investment for us, I figure we will never again have to buy window treatments. The light control they provide is excellent, and I don't find that they decrease visibility. I also don't know anything about insulation properties of wood vs. poly, but I do know that your windows will look very crisp and fresh with shutters. That's the direction I'd go, simply because I prefer the look.

Our wood shutters do an excellent job of helping to insulate and soundproof the windows. It's been in the 30s for a low here, and I can stand right next to a window and not feel cold when the shutters are completely closed.

Looks like you've got a very pretty space to work with!

Like Jen, I had plantation shutters installed, mainly to keep out the temps of the Tx heat~they definitely help. I absolutely love them, too! That's a very large window! I have to ask, do you *need* the arched portion also covered? You mention the morning sun and liking the evening stairs, and if that portion were covered, you wouldn't have access to opening/closing, so would lose those 'views'~just something to think about. But yes, I would go with shutters rather than draperies, which would probably cost a fortune, and fading could be an issue also.

Yes, unfortunately the morning sun comes from that very top portion. Sometimes we talk about sleeping in the living room during the summer because the a/c is more efficient there--but the sun would wake us up too early.

I suppose we could get an arch with moveable shutters--and some kind of telescoping rod that would allow us to adjust them.

Another question for you all: how are they for room darkening? The other room with a tall arched window--but not as tall as the dining room--is a bedroom that we're currently using as an office. But it has a sofabed for guests. Would the shutters block out enough morning sun for someone to sleep? I assume it wouldn't be as dark as black-out curtains.

If shutters are installed properly, your room will be quite dark when they are closed.

I'm used to seeing arches covered like this:

But I think this is an interesting look:

I Googled and found this article - http://www.washingtontimes.com/news/2012/feb/9/cover-story-window-treatments-combine-energy-effic/?page=all

This is part of what is said in it -

“A lot of products like blinds and shades are mostly just
energy-efficient in the summer, but drapery panels that are lined add
insulation in winter to keep the cold air out and the heat in,” Ms. Carley
said. “The most energy-efficient drapes have a ‘bump’ inside, a layer
of heavier material between the outside fabric and the liner that adds
insulation.”

Ms. Willard
said you also can add a black-out lining for greater energy efficiency,
noise reduction and room darkening. Insulating shades and Roman shades,
which are horizontal fabric panels hung over a cellular liner,
especially when combined with insulated drapery panels, provide a double
layer of energy efficiency."