I realize I am a day(or 2) late. I attended a quilting school and this is what I learned. The size of the block determines the size of your border. Thus 8 inch block would look better with a 4 inch border. Sashings should be 2 inches or less but more than an inch. Do I go by this? No! I just happen to like 4 or 4.5 inch borders. The teacher was a retired garment industry employee from NY.