Learn Sketchup is on my to do list. I use the IKEA and Reece online tools, which are good for quick mockups to help visualise the space with basic 3D rendering, but they can be a bit buggy and of course only have their own products to work with. I use Illustrator and photoshop for quick plans and mockups too, but only because I have a graphic design background.

Hey Nik Star, I've had a PowerPoint play with oklouise's edits. This is what I meant about garage entry to the pantry and a laundry in the garage. The red arrows are to stipulate to the builder that level access is required. I added extra garage depth to allow for the garage, that would definitely impact your facade elevation. If you remove the wall between the butler's pantry and mudroom you would have a SUPER PANTRY! But a true butler's pantry in that it was supposed to be where you would land with the veg from the garden so you would kick your shoes off inside the door, so I've noted a little bench seat there, then head in and wash it before heading over to the actual cooking area. Then if you get rid of the sliders and reduce the storage to shallow shelving on the middle wall you would have plenty of space to manoeuvre with mobility devices. For the washing labour machines - washer, dryer, dishy - try getting those mounted on plinths so the load on your poor back is reduced. I have dodgy joints so I am researching all the ergonomic ways to design work spaces to help me when I get to the awesome stage you guys are at with getting to build!

Like others here, at first glance I assumed the view of the water was to the east, but then realised from the sun diagram that north is up the page, so I'm guessing this might be in Bundeena? I agree with most of the other suggestions and have a few of my own as well, will summarise here: - the pitched roof dominates too much, I would suggest the new master bedroom suite has a flat room, similar to the new entry; - the garage is too small and can easily be larger, especially wider and the stair could go down the side instead of at the end; - the foyer/entry is too small for a luxury property, really just a stair landing. I suggest widening it to the line of the new bedroom, and also pulling the entry doors out further to give more space there; - car turning space is questionable. Maybe the external stair could flip over to the other side of the entry to give better reversing room, if it is needed at all (3 stairs???); - give more space to the ensuite, less to the walk-in-robe; - give more space to study, taken from bed room; - angled wall (in line with deck edge) in bedroom instead of re-entrant corner would make it more spacious and allow the bed to move forward with better access; - door to laundry from pantry instead of bath room.

what are all the walls floors and roof built out of? are the front bedroom and rear living room additions to the original house? is there a step down to the living room and what are the thick sections of wall at the end of the bathroom and study built of?...where are the original and proposed external doors to the backyard? is there a garage and driveway or any good or bad views and where would you have a dining area?.... it's important to understand the existing structure before considering changes eg the dimensions are inconsistent (varying wall thicknesses?) and you have removed sections of wall between the kitchen and lounge but these walls may hold up the ceiling and roof...do you know which walls are load bearing?