Roman shades would work here.

Or blinds

Top down/bottom up cellular shades will give you privacy and nearly disappear when opened. The top down is great, because you can retail the view of the trees, yet block the bottom part of the window. I'd get them in a color to match your trim.

I would do something simple like Hunter Douglas Duette shades in their opaque fabric with the top-down/bottom-up option. They can be easily inside or outside mounted, depending on space available.

Here are mine in my master bathroom. See how I have the top rail lowered to be able to see outside, but rest of the window is covered, but still allows light through. You can have them all open, all closed or partially open like my photo. This is the third house that I have used this type of blinds throughout the house and been very happy with them.

Roman shades might work really well in this area of your home. Please see the image below for how it might look.

Traditional Renovation · More Info