I like the seating idea and I would get roman shades.

I would only make it a seating area if you actually used it as a seating area. Would you sit there to put your shoes on? Otherwise I wouldn't see someone sitting there a lot since it's in the dining room. It looks a little high to be a seat too, but that could just be the angle. I would probably decorate with plants there.

I think it’s too high

What is the height of the ledge? If it is 30-32", I would use it as a serving table, providing it is close enough to the dining table. Seating height would be around 18".

How is view throught the window？ If the you could enjoy the view when you sitting there, it's good for sitting or get some books there and make it a place for reading. If not, I guess you could make it a little green house and still keep the photoes there.