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

hi my husband is a builder and I know about tiles a lot . there is nothing for wet area tiles . all tiles are floor and wall tiles. yea you could use rough surface tiles in wet area but it's depends on your style but you don't need to choose only rough surface . in wet area you must have to do waterproofing before laying your tiles . you can all choose from cremaic tiles to porcelain tiles. you just need to measure wall hight and width then tiles shop guys they we will work out how many sqm you need or give them your floor plan they can work it out.

It’s the wall colour that doesn’t look nice everything else is fine. Repaint the wall it’s easy and you want regret it , use neutral colours but not light go for darker and for the corner I would plant giant bird of paradise either in the huge pot or if possible in the ground but keep it well away from the wall to give it space to grow and give you tropical look and feel. If you are using pots you can have few of them they won’t drop leaves in the pool.

As you guessed , I just express my opinion . Some agree , some don't . Some houses which I have sold 20 years ago are still in the same decor , other people may not have purchased . I prefer a planned colour pallette and something that has a Wow , and I definitely won't have the same colour walls and ceilings all through a property . Some fast food restaurants do have the same colour all the way through , but even they tend to have white ceilings or similar . I do have a ( small ) stainless deep fryer that does great chips though ! As far as texture goes , I 100% guarantee I would have more texture than this house , to use the obvious comparison . That is why , if you go back up to my original post , I suggested a feature wall of wallpaper , and a painting -- texture and colour . I don't like grey or beige as primary colours , and in fact don't consider them pastels either , but thats pointless arguing semantics . I wouldn't have that combo , the OP would -- good on her . If houzz only had people that agree , it may be very boring .