Engineer-Joe, your ballast and blacktop experiment look terrific to me. As Carl points out sometimes you just need to step away from it and add some small touches. I think it is quite common to put something together and feel that it is not 'right'. I have to step away and give it time, look at it from different angles or different light before I see something else that helps make it 'pop' a bit more.
Of course, other times I rip it up and start over. I don't think you need to in your case.