I would hang the mirror on the wall where the art is now... it will reflect the beautiful foliage from outdoors.

I don't think you need the additional wall art. is that a bedroom hallway on the other side?

Yes, a bedroom hallway.  I will have to measure the wall to see if the mirror will fit. It may be too wide.

Measured. Mirror is 40" wide,  wall is 44". I like the idea of a mirror on that wall but I think it'll have to a slimmer one.

Place the mirror on the bare wall. Turn it into a little escape area.

It might be a great area for a small chair and desk, something that would be pretty but also a great homework area/ bill pay zone/ creative writing space.

IMO the bench is great the mirror serves no purpose but a really large piece of art would work but I assume this is going to beroom spaces so why not a nice grouping of family photos IMO a perfect spot for those . I like the idea of a little reading nook but thn the bench needs to go into a bedroom or in the main entry. to allow for a nice chair , table and lamp.

I think it looks great minus the mirror. I'd scoot the bench right up to the left wall and add sufficient pillows to make it comfortable for actually sitting for awhile.

If you are looking for an all purpose mini-chaise reading nook, then you need to add lighting for nightime. If there is no outlet get a cordless rechargeable floor lamp from Zafferano. They're great.

For a reading nookI would also add a low small stool to use a place to put down a cup of tea and a cell phone.

That's a good point....decide on a purpose for the space and that will determine how to decorate.

Also depending if there is an electrical outlet here or not.

The space is cute, I don't think you need to change anything but the mirror seems in the wrong spot.

Since you want to keep the bench (if it was my house, I'd angle a chaise in that space!):

Try the bench on the longer wall. Add pillows so that it might be comfy to sit on. Put a large piece of art above it, and a tall plant in the corner on the other side of the window. Add an asymmetrical faux cowhide rug to define the area.