I did the same colour pallet as your describing on a new build. Black kitchen window frames, concrete floors and timber accents. Not quite finished yet but I'm happy. Must tell you that Laminex have just brought out a matt black that doesn't show fingerprints for your black kitchen cabinets. Basically I used concrete, accent colour was black, all walls and ceilings in Whisper white and then added timber. Hope this helps.

What a lovely house, a paint update will look really exciting! Contrary to all the colours you've chosen, I'd go instead with a warm grey (hint of taupe in it). It will always be classic, would look amazing with fresh white window frames and dark charcoal eaves (e.g. Dulux Monument). Cue my favourite colour: Dulux Dieskau. I just think there's quite a large area of uninterrupted rendered wall so I'd worry that if you go too bluish, it could look to be verging on pastel and a gingerbread house type effect. My brother painted Tranquil Retreat on his rendered Victorian and it has come up more blue than he'd thought (actually he was also considering Milton Moon). But of course, test paint a few walls sections with different aspects and check during the day from different angles (and even across the road)!! Actually there's another photo and paint colour I love that reminded me of this, I'll try and track it down.

Two main points -- the inspiration pic is a modern build ; and it actually has quite a lot of off-white . IMO those are both important -- a 70's or 80's brick veneer painted or rendered dark won't have the same proportions to the windows , even the roof overhangs , etc -- it may just look like a tarted up brick veneer place . By doing the extension in cladding , especially if it doesn't include some of those design features in the 'original' area may even emphasis that . Quite possibly you , or your designer , have allowed for all of that , and done an integrated upgrade , but when I read your outline , it isn't clear , So to get back to your question about colours , I'd make sure I had at least some off-white ( a fireplace rendered to a sharp square look as per the inspo pic and/or a shorter wall done the same ) ; some battens in similar tones to your deck , etc . Even the inspo house IMO would look better with brighter furniture -- the sunny tones like red , orange , yellow , even green would all add to that place IMO ( probably just 1 colour , a mix is harder to get right ) .

I like the first one more I think, both are really nice but it has a fresh look about it that I'm more drawn to