If you have kids they will still curl up on a thirty window seat and read. Mine are about 25 but the extra five inches would not stop my kids from using it as a favorite spot.

I think it looks pleasant as is but if not a pillow maybe green plants that will thrive in the natural light the window offers or keep as is.

I would have a custom pad made for it, not too thick so as to add to the height, but maybe 2". It would look so inviting! I think lots of window seats are higher than traditional seating height and seem to be a favorite place for many to sit/lounge.

Custom cushion.

A lovely room. I do understand your dilemma. 30" is higher than standard seating. You are also limited from the front of house exposure of covering the windows. Have you considered removing the bench ledge altogether? I think it would be more functional scooting your chair into that area as a reading nook or even removing the bench and placing a lovely chaise there. I think books, vase, or statue would look a bit awkward. You could install a piece of marble, stone, or stained wood and treat as a coffee table or serving piece. A large tray with books, a tea service or candlesticks might work. Good luck.

More than the height, the lack of wall surface to prop against would be my hesitation to use as a window seat. Leaning up against the glass doesn't sit right with me for some reason. If you fill it with plants you would have a solarium feel to your room. Before seeing the picture I too thought that is a lot of space to not have IN your room vs next to it. Is there something in the box? Removing it would be a pain with flooring/walls to fix but it is what I would want in the end.

Thanks to all for your comments. To answer your question, i use the space underneath the window for sorely needed storage. It's a small house. Besides, i couldn't go through the expense of the construction to remove it.

+1 for a thin cushion. It is a lovely spot for a nice reading nook!

arcy_gw is right though, the lack of a wall to lean against is an issue. Maybe a corner bookshelf? It would cover the window, though.

It doesn't look to me like the ledge is really deep enough to provide suitable seating, even for kids. I think you're already on the right track with your thoughts of plants or artwork/sculpture. What style is the rest of the room, and what sort of art objects do you like?

One lady in my neighbourhood does a lovely seasonal display in her box bay and updates it for every holiday. I could never do so but I love it to death and I'm always curious to see what she puts up next.

I agree that the seating area wouldn't really work. I guess i lean towards traditional but love to add a bit of the unexpected either in art or fabric. I love to mix traditional with contemporary. I guess I'm all over the place, but love to play around until it comes together and reflects me.

A metal sculpture of trees? Like the ones you hang up on the wall. Or how about a fireplace screen? Sounds strange, i know, but just running it by you guys

You're really only limited by your imagination! (Well, and what you can actually find in the stores or make yourself to fit the bill.) If that were my space, I think I'd focus on adding sculptural items - three at the most - and keep it artsy and uncluttered. I too like traditional and contemporary things together; I think that provides so much interest! Here's just a little mock-up, and this might not be your style at all, but hopefully it will give you an idea of how a sculptural piece would look in this space.

Omg love it! Yes, that's what I'm talking about....love the balance and the overall look. Love these mock ups that you talented people do!

I agree with Idaclaire. I have a very large coffee table and I do a seasonal coffee table vignette - spring, summer, fall, christmas and then winter. If you google coffee table vignettes or sofa tablescapes it may spark your imagination. I just go to Home Sense and pick up a couple of things each season.

You could anchor it with a plant and then add favourite things around it. you may already have some things that you can start playing with. And don't forget you can do small artwork or family pictures and prop them on a small easel which are affordable at Michael's.