I see this is a very old thread , with lots of comments . I've just skim read them , but I haven't seen anyone suggest anything like my 'top-of-my-head' idea -- I love the wood , and the white contrast , but pretty boring . Whats your favourite colour , or what ties in with the other rooms ? It might be blue or red or yellow or orange or green , as examples . So paint the skirting board and around the door a pastel shade of your choice , and add a small 30cm x 30cm abstract painting featuring that colour as the primary dominant one , above ( or possibly below , or maybe even get 2 matching/complementary ones ) the control panel . One lighting crowd suggested glass shades -- I'd actually go for someothing large but wooden , in much the same shade as your floors and steps , with LED bulbs -- you can get some stunning ones around 80-100 cm in diameter ( sort of a star ball shape ) for $300-400 . Total budget then $500 plus a painter and maybe electrician , unless you DIY .

The mezzanine and storage spaces. Next to the mezzanine the builder installed a little door for us to give us access into the roof space. As the kids are using the mezzanine as a chill out area to watch TV play video games the storage now holds their board games, art and craft etc. The girls painted the walls to brighten it up. As the ducted system didn't work too well at the front of apartment we had to install a split system AC to cool down the study and the two front bedrooms.

This looks like a pretty good start but keep in mind that you already have a lot of hard surfaces (tiles floor, stone benches etc) that are going to bounce a lot of sound around that space. The big trick with open-plan living is to try to keep the ambient sound levels muffled and soft. Make sure that you put nice soft felt floor protectors on the feet of everything – you don't want to hear each time a chair or stool is dragged across the tiles. Don't even think of adding a glass-topped table to the mix – every time a glass is put down, a plate is shifted or cutlery moved it clinks and bangs (not to mention that they are the very devil to keep spotlessly clean and shiny and if they're not they look horrible). A timber table does not have to look 'woody' or clash with (or match) the floors – timber can be painted or stained and there are some very classy looking laminates out there that are easier to live with than glass. As others have said some rugs defining the zones within this large room will help to soften both the look and the sound, as well as introduce some colour. I also find the spacing of the pendant lights rather clunky – try spacing lights across the island rather than stringing them out across the full width of the ceiling.

You could add a chaise lounge or a comfy chair and table for a reading nook or an office area if you need one, a computer area but whatever you do don't over clutter it keep it sleek and sexy and or a comfy chair as suggested with a little side table for reading, I also like the idea of a place to put coats, shoes etc if you must enclose it. Maybe even a small wine bar? with a couple of stools. I decided to google is and will give you a link to many pics to give you more choices. https://www.google.com.au/search?q=pics+of+what+to+do+with+space+behind+floating+stairs&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjFy-n9p4vZAhUEF5QKHSvhAOMQ7AkISg&biw=1280&bih=893