Full built ins across your window wall would look amazing. Maybe consider keeping drawers along bottom for a clean look and hidden storage for not so pretty items and then shelving above. Taking it all the way to the ceiling would look great too. For the short wall next to the door you could think about shelving to the inside of the window seating for a different look like the images below. We would love to see your final outcome!

We have almost finished our ensuite, and as we are planing for a wheel chair future for myself.- We require the vanity mirrors to accomodate my seated height and my partners standing height. I had presumed it would just require 2 pivoting mirrrors. I just am having difficulty finding them in Brisbane. Any clues?

No-one seems to have brought up what , to me , seems like the second most logical suggestion ( admitttedly , without knowing the planning rules ) . The logical still seems to be to sell . Failing that , I'd look at extending the study , taking in the courtyard , alter the internal door ( suggestion - a single door on the 'right' side of the existing study doors area ) , add an ensuite ( relatively easy as the existing bathroom is just through the wall ) , and make that room your master bedroom with en-suite . Move the ranchslider , or add a roof to floor window , to get natural light into the new master , and possibly add a skylight or two above the dining room , as it will lose the ranchslider . Not perfect , but if you go up it will be costly , there are engineering issues , matching materials , new roof , all sorts of logistical problems . 'My' suggestion cuts down outdoor space , and may exceed the building to land-size ratios , but its so much easier building , engineering , roofing , plumbing and materials matching wise , gives you all or most of the space you are after , so IMO way more bang per buck . Having said that , only you know your priorities , budget and what you are happy to give up to gain .

Thanks very much Paul, I really appreciate your ideas and feedback. We like your plan and agree this plan gives us a more practical user space. We're really focused on making it all "feel" right and would also consider how this canterlever out over the existing master bedroom would feel/look from the verandah and living area looking out. We're also extending the study out towards the side boundary by just over a metre and removing the existing linen to increased bedroom 2. Bedroom 3 will be the kids chill out room/spare room and the other child will move to the original master. New Linen will be under the new stairs and we're also building some storage into the study and extending the garage to the front boundary by 1 metre. We dont' feel like we need another living area (or massive house to clean) as we already have two separate living areas and bedroom 3 will be for the kids to hang out in. And this is why I originally posted (and which you've clearly identified) - because I'm stuck between having a limited use gallery landing to provide volume and drama in the stairs, and as you say I don't want to kick myself for not making the gallery area a more practical space. I know other families with parents retreats that never use them, so I'm conscious of this too. I think I was probably hoping to achieve the same footprint with the nook a little wider. I thought last night I could reduce the ensure/robe depth to 2.2 to 2.5 (and increase the nook to 1.7 to 2.0) by moving the toilet to the end of the shower. Maybe this would work as a compromise.