All the suggestions above are perfectly good. However, when you have a house that is entirely painted, the options are so endless that it's easy to get stuck. I'd advise either finding photos of comparable homes in colors that you really love, and reproducing a similar palette on your home… or upload a picture of your house to a colorizing site, and play around with various combos. Sherwin Williams has a Color Visualizer that is decent. I don't mind a white house, but feel that the black trim is a bit harsh. On the railing especially- it feels like it is outlining itself too much. Reduce the contrast between the body and the rail and it will enhance the house rather than overwhelm it. You have a lot of choices, so just experiment and go with what resonates with you.

Oops! Your trim looks grayish blue to me. Sorry, didn't see it is charcoal until afterwards...well in that case, I think I would still do gable and wrought iron as mentioned but then try a bright yellow, like SW's BEESWAX is paint color. Are you in the islands? Sorta has "that look". Envy : )

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!

I don't know how hot it gets in Auckland in summer (I've only ever been to NZ in winter!) but if it gets hot, then go for a pale colour. Dark roofs should be kept for cold places!