Simple chords that get attention and keep it

You don't really NEED complicated chords or super-intricate melodies to create captivating music. Sure, they can help. A whole world of amazing possibilities opens up the more harmony you know. And yet, what's often even more awe-inspiring to me is how simple uses of basic harmony ideas can keep my attention and draw me in just as much, and sometimes even more. By small and simple things are great things brought to pass. Sometimes, all it takes is 3 little notes. Simple notes. Notes right...