Interesting 'rules of the road' for hanging artwork... I'll admit I prefer to just play around with the hanging templates until it feels right... Once that's done (and double-checked with a pocket mirror to make sure it's truly balanced)... Then, I like the idea of checking heights for uniformity (but I just use my nose, shoulder as a guide!)
A great photo of my favorite place in the world. When people take photos of the Eiffel Tower they all take it from the same angle. The angle that this person used along with variety in textures makes the photo unique.