Use cove or corner molding type pieces?

Select a tile that has matching trim pieces for edging, or matching bullnose pieces that can be used along the edges.

I really appreciate the visual here. I'm going to be tiling around a long BS window, I think. The counter will come right up to the lower part of the window, but that doesn't address how to box it in. I have been leaning towards tile and away from wood trim, but agree that edging would be nice.