I used Berroco Comfort Sock yarn to make these. They are incredibly comfortable with lots of stretch in all the right places. While the size given in my pattern fits a medium woman's foot, I added stitches plus used larger needles and knit the same pattern for my husband. He loves them, too.
To make slight size changes try using a larger or smaller set of needles.
9.5 sts = 1" unstretched waffle rib stitch pattern