A top window treatment like a valance or Roman shade that would sit just on the upper wall and not cut any light would give the area some pizzazz. The cabinets do look like crown moulding would make them more substantial looking but I would not add cherry moulding around the window. You could also select a plain subway tile or a vertical mosaic in colors that work with both the green and granite and 'frame' the window in tile, all the way up to ceiling. A very nice contemporary look.

I also think a roman shade/ blind would look nice like in the picture. I recommend 'Eaton Stripe Linen/Cotton Fabric Camomile at Laura Ashley' for the fabric of the blind. The colors complement both the wall olive paint and the cabinets warm color. Will lighten the space and make it pop! Add a flower vase the bottom left or right . White orchids will look lovely

What is the style of your house? You have rather traditional shaker cabinets, and so the window should be wood-trimmed. Get a finish carpenter to show you some options.
If it were my kitchen, I would also take down those 2 upper cabinets on either side of the window.

Put a plantation shutter up and the job will be done! This kind of window is perfect for a vinyl or composite planation shutter. You can get them with a nice 2 or 3 in casement that will really help accent the window.

Roman shade from the ceiling; keep it lowered to the awning line.

Shutters are nice, but the gooseneck faucet on your sink is going to be an issue. A good shutter company can custom make a set of shutters that can address this issue. If you go that route, MAKE SURE you know what the company is going to do to address it for you. If they can't explain it or tell you that nothing can be done about it, FIND ANOTHER COMPANY to work with.

Alternately, we have installed simple cornices or decorative valances to add a splash of color to a window like that.

Crown molding will make a world of difference, it's the finishing touch you need.

I agree w/ the valance or Roman Shade mounted as high as possible. A shutter would be an upkeep nightmare..........food and water splatters.

A shutter would be super easy to keep clean and maintain because all you have to do is wipe the shutter off if you get something on it. Roman Shades are much more likely to get stains on them that are going to require professional cleaning. Just something to consider.

Not always easy to reach a window over a sink for cleaning purposes. Plus it blocks a lot of light. Shade.