Our personal preference when looking at double storey home design, is the master bedroom downstairs. Think about the future and ages and physical abilities of older occupants. If a master bedroom with all your “wants” are downstairs, (bedroom, bathroom, laundry, kitchen, living, garden) there would be no need to climb the stairs when not able.

I would put the minor bedrooms upstairs. Kids have younger legs. For re-sale - families with babies want to be near them, those with teenagers don’t and empty nesters want to be able to “close” off unused rooms. For most family stages, inc your own aging a downstairs main bedroom is a selling point.

Definitely the master downstairs. I wouldn’t sleep upstairs with younger children downstairs, I wouldn’t trust teenagers downstairs while I’m upstairs and I wouldn’t want to climb stairs now I’m older. When we sold our large 2 storey home a few years ago, we lost several buyers because we didn’t have a downstairs master.

also prefer master suite and study downstairs but would also sacrifice some upstairs bedroom space for a more comfortable bathroom for sharing but could you please share plans for existing ground floor to better understand what space is available

If having the minor bedrooms upstairs for young adults. I would have a bathroom with two sinks and a large shower. And a separate toilet with hand basin. You have the potential for 4 or more adults to share that space. You need separate facilities. Eg: people can use shower if someone else is in the toilet. The toilet basin can be used for brushing teeth, if someone is using the shower room. A multifunctional space is best for all occupants.

. Currently

3 equal beds upstairs with toilet separate to bathroom and study/nursery and master downstairs.

The floor plan says "proposed ground floor plan option A ? is this from an earlier upgrade

And where is you outdoor space. While the roof is off I would look at improving connection to the outdoor space and possibly moving fridge to open up the kitchen to living space.

Upstairs master suites definitely boost resale value. A study is nice, but a walk-in robe is probably a bigger seller. Think about what buyers in your area want most.

When we built our place, we had the same debate. Ended up keeping the master downstairs because it was easier with young kids, but I’ve seen plenty of homes where the master is upstairs, and it does add a bit of privacy, which some buyers like. If resale is a big factor, maybe a flexible room upstairs—like a study that could double as a bedroom—gives you more options without committing to one setup.