I think you need to move in all your furniture before you start considering window treatments.

Use fiber shades or romans instead of drapes.

Check out the link to this rustic Med beach house where they've been used a lot.

Ninigret is right but, you have a gable ceiling so maybe a very light inside roman shade with a long drapery installed with this easy installation piece keeping the ceiling style.

First decide if the windows actually require window treatments. Sometimes they don't. If you select drapery panels, make sure they are mounted high enough in the room.

I would lighten the stone on the fireplace like you see in this photo.

Here are some options for windows near fireplaces.