Put a plush seat cushion on (4-6 inches high) and add a few decorative pillows (minimum 12 inches) and it will close the gap. Since the window is so high, do you still have privacy issues(can people see in)? If not, I would remove the curtain. I think your nook has charming potential!

I agree with Sister Sunnie about a 6 inch seat cushion, but I would also add more depth to the seat so you can sit with your back in the corner (with pillows) and extend your legs towards the camera. If you need to darken the window to sleep, add a simple shade instead of the curtain. I would add a reading light too.

Woah, Decoenthusiaste just performed a Vulcan mind meld and posted the picture in my mind that I tried to describe with words. Nice! :)

Can’t see you space but looks like a great spot for a closet

@decoenthusiaste this looks great and very comfy, thanks. We might build a higher platform and add cushion like @Sister Sunnie suggested. @Kicksychick thanks for the shade idea, people can't see in but there is lot of sun that comes through this window in morning.

Based on the picture as well, the windows are likely going to require replacement at some point in the not to distant future. Based on the spacer movement in the half round.

Update:

Hi, thanks to all your wonderful ideas and design Inspirations. We finally finished our Nook transformation. It’s a DIY with lots of storage.