Carpet. Ugly, grey, literally-threadbare carpet. It is something we intend to get rid of, but carpet here isn't easy, in choice or available installers. But we'll go again with it, with something industrial-strength like we had at a previous house, a warm, dark brown most likely, to deal with the dogs and the dirt and the everything else that still manages to get inside past the mudroom.

Look at Sydney Mixed Blue Gum or Tallowwood perhaps. A hardwood floor will look awesome no matter what species is chosen, you can't really go wrong.

Definitely depends if the ground floor is slab on ground or lightweight structure. If it is lightweight than concrete isn't an option anyway! Concrete is a hardy material, but it needs to be protected during construction. Timber integrates that warm natural feeling that can often make or break a home! What materials are being used for the remainder of the design. If there is already a lot of timber, it can be beneficial to incorporate concrete or tiles so that the timber isn't overbearing. If the remainder of the palette is simple white plasterboard, than the warm timber floor is often beneficial.

You can install real timber either direct stick to concrete or 'planks on ply'. Perhaps get a reputable timber flooring company to come out and advise. You don't necessarily have to get engineered or laminate