The proof was in the prizes at Marceline: pictures with a strong silhouette did well. Nyle Gordon's coal elevator took best in show (some photos courtesy of Rachel Neil)
Deb Baughman's watercolor of the same subject got an Honorable Mention.
I also got an Honorable Mention for this Harley which I painters quickly at the end of the day during the Wine Stroll.
Silhouettes usually thrive in backlit situations, so if something doesn't thrill you from one angle, walk around it - the shape may come to life against the light (or contre jour as Pepe LePew would say).
Here's a nice example by UK watercolorist John Yardley
Two main things make a shape interesting:
1. COMPLEX CONTOURS - give your eye a fun ride! The shape should interlock with its surroundings, not just bump against them.
2. A LACK OF BILATERAL SYMMETRY - if you cut out your shape and folded it down the middle the two haves shouldn't match. That means simple rectangular or oval shapes may need to connect to other shapes to form a more interesting conglomerate shape or connect with their cast shadows to do the same (backlighting achieves this).