trim should match the cabinets, then off white paint for the space around it or what ever color the dining room is.

I would keep the wood stained frame of the window and continue the granite up the wall and across the top. Then add 2 interior mount faux roman shades in a material that compliments the kitchen. You do not need to worry about sun exposure or privacy so making the romans non-operable is perfect and well priced. The picture below is just the look of time going all around a window and the style of the shade NOT the pattern or colors:)

HI -- Yes continue the tile up and around the window and either have the frame the same as the cabinets or paint the window frame dark like the tile . Because the window faces into the sunroom ,you maybe don't need any window covering or accent . Maybe this is something to do instead ... wallpaperforwindows.com.

HI -- Actually looking at this more I think I would not have the window casing trim and opt for just the tile edging in a chrome which would be a much cleaner look .

Ditto for Angel's comment!

Once the recessed light is installed, add a simple valance above the kitchen window. You may choose plain white, white lace, or your favorite accent color.