reluctant to lose the convenience of outside access to a toilet my suggestion sacrifices a little space off the lounge and bedroom to keep the extra toilet and use the original laundry space for a bigger ensuite with separate toilet and double vanities, the new extension makes a more spacious wiw with only standard doorway openings to the new rooms but the ideal outside door for the laundry will depend on the location of the drying area and you may decide that a western door or no outside door (and walk through the verandah?) could both add more counter space to the laundry and, much as i like the gable roof for the extension, it would be interesting to obtain a comparative quote for a simple skillion roof (and raked ceilings for the new laundry and wiw) that may save a lot of extra roof structure that doesn't add anything to the inside of the new rooms or streetscape and could be much cheaper..

it should be easy enough to use bed 2 as space for an ensuite but that means losing a bedroom...do you have any other long term plans to add extra bedrooms, new kitchen etc eg the old extension seems like a much better location for the kitchen, make a bigger dining area and maybe add a screened room across the back to take advantage of your good climate but neither idea solves the problem of the missing bedroom, could the living area be converted to extra bedrooms but how you would access the clothesline from a laundry in the garage...is there space to add an external door on either side of downstairs? maybe the cellar would be a better location for the new laundry with closer access to the stairs and an existing external (front) door and add laundry shute from the upstairs bathroom but making scaled plans is difficult as the real estate plans are inconsistent ...please confirm the dimensions of all the rooms (including bath, toilet, biws and hallways and i can make a better scaled plan to share

Beautiful bath needs pride of place opp door. Freestanding baths take a lot of space so have to compromise somewhere else, So I would go opt 3 but swap bath and shower location and cut shower back to 1200 x 900 which is more than ample. Opt 4 if you want the bigger shower but cut vanity back to 1200 which is not as great for a family bath.

I also like oklouise plan. good insulation is the key. In your original posted plan, Maybe change where the beds are positioned in the room. I think there is some bad feng shui if your head is backing onto a toilet. Apart from the noise factor, every time the toilet is flushed.