Although I like the way that seams nest together when you sew seams to the side, I like the less bulky appearance of seams pressed open. If I have quilt blocks that are sewn exactly the same and will be laid out exactly the same I will usually press seams to the side so that seams can nest. But, if I have blocks that are going to be rotated so that you can't quit figure which way the seams will go, I'll press all the seams open. If I have numerous seams, like with a star, I press the seams open. Clear as mud, huh?