Your deck will be amazing. It has fantastic form and plenty of architectural interest, it will add enormous benefit to the front facade and street appeal. I love your palette, it is simple and still has point sof interest. MY suggestion would be to use a combination of your exterior colours applied where best to highlight the deck structure and either tie in, or accent against it. Ding all of these things by painting the lower retaining section in the base grey the charcoal colour to continue and blend into the lower floor brickwork, also do this charcoal on the upper deck frame which is also the roof of that entry way. I am trying to say that thick timber which trims the deck. And the slatted section of the stair wall which acts as a breezeway in the light grey- why? Because the open sections of the slats will always appear black as you can see through them to under the satirs, and the light grey slats will stand out and feature that shadow line, perhaps even use liting to further enhance this detail. Lastly, the stair treads themselves left natural, like an architectural contemporRy stAtement, the natural timber tones will be rich and sophisticated and act as art inviting you to the home. These stairs would really pop and be commentedon at street level, also consider lights in each tread, perhaps the slatted wall side to highlight both this and the stirs for night practicality. What a stunning entrance. The natural character in rich timber tones will warm the grey, keep it contemporary and not introduce personalized colour, which can take away from street appeal. This on the other hand, appeals to everyone. And greenery, landscaping will only take this to the next level. Literally!

We just stained our section fences with Wattle Ebony from Mitre 10. Was looking for a charcoal color too, not much flexibility in color options with stains from the shelves at store. We sprayed on, rather than brushing. Is cost a concern? One of our to be neighbours was doing there fences at the same time with paint, he said he used nearly 100L of paint for 2 coats, we used nearly 50L in 2 costs - had similar amount of fences. I've included photo of it after the 2 coats

after watching my daughter and her husband agonize over the way their expensive timber floor has not held up well after 3 years, I would recommend tiles/wood look tiles with under heating. Their beautiful warm expensive floor looks like it always needs a clean and polish, not from neglect, they have cared for it well. One of the boards now has a slight and painful moan when it's stepped on :-( I grew up in a completely wood floor home and although it looked wonderful, my Mother hated it. ....and the mats ! Wood is a lot harder to maintain than tiles ,(no matter what the die hards say) the modern wood finishes are much better than they used to be.... But a piece of wood is rather arty no matter what it's used for and it does demand to be loved and cared for.....and if something goes wrong it's a lot more expensive to fix than sand and cement. Ultimately you have to be happy. BTW underheating tiles is warmer than timber :-)

Plenty of comfortable seating