I had a recent dilemma. My ds has two windows, but a large covered porch outside of those windows. He wanted the same med/dark blue that is in his brothers' room, but his brother has larger windows, a tall dormer and no overhang to deal with. I wanted to go pale blue, but knew I wouldn't get away with it. We chose a blue that wasn't dark, but has some intensity. Similar to this (the exact colour we chose is in the big book, but not on a colour swatch).
https://www.dulux.ca/diy/colour/colo...=70bg%2044/129