Crown moulding added beneath a custom-cut enlarged window sill.
Or, in our case add them. We had our house built and I couldn't believe it when we moved in and had no window sills and only 7 foot ceilings. This is going to be my honey do project for 2015 (eek, I have 10 front windows alone!
Make a farmhouse window - add window trim to beef up a plain window with no miter cuts in sight!
Window sill idea for replacement windows
Clean window sill: A few magazines/books, plants & candles