I like the two different wall colors. Perhaps pink for the closet? For a similar paint shade, try 'Razorback Road' from the Dulux 'Colours of New Zealand' range. Available through Guthrie Bowron stores.
a recessed nook becomes a headboard for the bed. I think I'd take the nook all the way to the ceiling to avoid it looking like you put the bed in a repurposed closet; and put the ledge up higher, so that you can recline against the wall