I cut the fabric up into 9 1/2 x 6 1/2 inch large patches then laid them out in a hopefully pleasing pattern. As I had about the same amount of blue fabric to white/gray fabric, I thought this pattern looked quite nice.
I decided not to add any batting, but just to sew it against an old duvet cover. As I wanted the blanket to be as light and lofty as possible, I also decided not to quilt it, but simply tie bind it in the center of each block.
This was one of the fastest projects ever (especially for something this size) and I couldn't be any happier on the outcome.