I love greyish coloured/weathered looking timber. I have done a concept design called "beach house" where I used the same coloured timber decking....I love it! Images are on my Houzz profile and website if you want to look. All the best :)

I agree with Mel N, all charcoal with some pots of lime green grasses in perhaps tall red pots. Charcoal will also cut down the glare from the water. Tall pots as below will look great or shallow pots with bamboo.

It’s the wall colour that doesn’t look nice everything else is fine. Repaint the wall it’s easy and you want regret it , use neutral colours but not light go for darker and for the corner I would plant giant bird of paradise either in the huge pot or if possible in the ground but keep it well away from the wall to give it space to grow and give you tropical look and feel. If you are using pots you can have few of them they won’t drop leaves in the pool.

A light grey large format tile (600 x 600) would be great. You wouldn’t get the glare that you get with white, will look almost as light as white in the sun. It’s modern and would go with the Monument colour.