The brown sashing is nice, even thought I love blue. I would place them boy/girl/boy. To put them rows of boys/rows of girls would make the quilt look stripey. As for the setting of the individual bears in each row - my rule is to lay out the squares, look, then squint. The squinting helps me see if one color is too much in one place or too much pop in one area - then I move them until everything seems balanced. How's that :)
Patricia