Rhomboidicity of Kites

Topic:
Kite
A kite is a quadrilateral with perpendicular diagonals that in certain circumstances is a rhomboid. A rhomboid is a kite that in certain circumstances is square. Can you devise a measure of rhomboidicity of kites that allows you to tell how much more rhomboidal one kite is than another? Can you devise a second and different measure of rhomboidicity of kites? Under what circumstances might one such measure be preferable to the other? [See the "Polygon Explorer" and "Polygon Synthesizer" applets on the mathMINDhabits website]