Height rules supreme. Valances to the ceiling and panels to the floor are always a graceful look. Invoke those elements and principles of design. Line is second to color in setting the mood. Use vertical line to say elegant, formal and to set the tone.
Window treatments have a silhouette; just like Fashion use it to your advantage. Mounting on the frame blocks the light and view and makes the window look stunted. So mount your treatments at least 4” above the frame to give your treatment couture flair. (Remember mounting”on the frame” distinguishes ready mades from custom treatments.)
Blank wall space above the trim bother you? Hang roman or roller shades behind them to give illusion of height.