Good stuff.....except #3.
Selective coloring can work, but it's a 1 in 10,000 kind of thing. Maybe 1 in 50,000.
#1 has a centered horizon.
#2 has the bird centered.
#3 has the waterfall centered.
#4 has the Space Needle centered.
Centering can work too, but like selective coloring it's not all that often.
The reason centering kind of falls short is that it drastically reduces the tension in an image.
The first place a person usually looks when presented with an image is called the 'eye line'. The eye line is 1/3 of the way down from the top of the image. That's one of the reasons why the rule of thirds can be so effective as a guideline for artistic composition.