Without seeing the rest of the space, it's hard to say. You can consider tiling midway up the window so it takes your eye up.

Bring the tile to the top of the lower sash which would be half way. If the tile has a bull nose then tile into the reveal of the window. If the budget permits and you are getting a solid materiel then have a window sill fabricated and some small pieces to cap the top of the tile

This is also a white kitchen with done up with beige travertine tile over the sink and going all the way up to the ceiling.

The homeowner also tiled over the range going all the way up to the ceiling

I don't see any trim on this window? Do you have trim on the other windows in your house? I would think about adding 3 in trim all the way around and just taking the tile up to the bottom of the window. All the examples posted so far have what I describe.