Hi, I'm building a home with polished concrete throughout. I've noticed this post is a month old, so have you decided yet? I didnt' go with the usual aggregate as I felt it was too "busy". The concrete had charcoal dye added to the mix. I've seen pictures of it done with light colours as well and it looks good.

With a level issue like that- you are either going to need to grind it right down by 30mm (all good if you want aggregate exposed, but tricky if you don't know how thick the original slab is), or lay a topping slab on top of what you already have. These topping slabs can be like Pangea (thinner 5-6mm) or thicker regular concrete (40-50mm). The regular concrete is cheaper and you pay by the cube (m3). You then need to pay to have it ground and polished....anything from $50-70m2. Polished concrete is not a cheap option. You might want to look at concrete-look tiles, that way your tiler can make the level adjustments.

love your Jarrah floors with grey..have you considered paving paint as the cheapest thin grey coloured flooring??

I would recommend going a darker colour too! We have done it several times with clients who (like yourself) can't see what the finished concrete aggregate will look like until afterwards and the darker the better we have found. Like Zaffa said, it would be amazing if you could extend the concrete into the bathroom, as that can be absolutely beautiful and this aggregate look is a fantastic addition to a bathroom. However if you want to break it up I would go for a dark charcoal (large format) tile so you don't risk clashing colours. Darker bathrooms are really stylish so you don't risk sacrificing on style. Don't hesitate to contact me if you need any help selecting specific tiles as we know how overwhelming it can be and are happy to help. Best of Luck, Jordan from JFI Studios!