It would seem most efficient to intercept the tile as early in the process as possible. The problem with that is the nature of color. What might look like one thing in a tile showroom or warehouse, can look like something else somewhere else. The only way to determine how it will look in your yard is to have it in your yard. The perception of color is influenced by its environment. Sun, shadows, wet, dry you've mentioned. But the color of surrounding elements plays a huge part, too. Your perception of the color of coping and tile and brick all affect each other, of course. But so do other things in your line of sight. The color of your house, the water, the sky, your fence, your plants, your furniture, all affect your perception of the colors of your pool's materials, along with everything else. For example, the colors of these pairs of inner rectangles are identical!
View attachment 171952
And that is not even considering (and is a different effect than) reflections! Adjacent colors affect your perception, but colors reflecting off of other colors does too! Two different things.
It's just the way are eyes and brains work. And not all eyes and brains work alike. That's why some folks, including some here, can honestly say it all looks fine, because to them it does. When to others, like me and you, it doesn't look quite right. There's nothing wrong with any of us, it's just the way we are... Like how some of us sound great when we sing, and others
think they sound great when they sing!

Or like how the colors are making you crazy, and maybe your spouse is thinking you
are crazy!
So get the new coping in your yard. Take each piece out of the box. Lay it out around the pool and spa. Watch it for a day or two. Get it wet throughout the day. Decide to keep or reject it. Then proceed to mix'n'match and swap each piece around until the overall effect is pleasing. Then instruct the PB and his crew to honor exactly the layout you've established. They'll either roll their eyes, or appreciate that you've eliminated the possibility that you'll be displeased with the end result, because it'll be on you. Or both. Who cares. You'll never see each other again!
But a final warning, that folks like you and me have to deal with. The more particular we are, by choice or genetics, the harder we are to please. Be prepared that no matter how hard you try, it might not end up perfect. And it might just look that way at 4 in the afternoon. Or during a cloudy day. Or whatever. Or... it might just look amazing to you all the time!! That's the plan, anyway!