I contemplated a bold green floral first up (here), then ticking (here) but have now ruled both those out. I really like the Warwick geometric fabric "Vishna" in Sky (bluey-green) or Quartz (beige) which is surprisingly economical (particularly if bought from the US via this etsy store) or I have always been a fan of the less budget friendly Fretwork Linen (though the pale green colourway is too "mint" so maybe the greige / dark grey would work better?).
But I am a little concerned that given the relatively "structured" nature of the bed-head and lamps means that I need to use something a little less structured and formal on the couch to balance it out.
I love the Finn Jufl sofa at Great Dane which I have seen covered in a variety of different plain felts and wools (there is a beautiful sky blue one in store at the moment).
And Edit has a similar shaped sofa in a brilliant plain pine-lime colour in its window at present. So maybe a plain linen or felt - in pale blue / green or even navy - is the way to go?
Then last week I came across these lovely prints from Pure Style Home - beautiful soft muted colours and organic prints. The large Live Paisley and Wild Chicory are my favourites. Perhaps a large print could also be an option?