There are some pattern stitches which move diagonally. I think this gives the hat a nice dynamic quality. Here are two hats that use this diagonal movement. I was happy with both of these hats when I made them.
As with most of my hats, I was again using Patons classic wool.
I follow another blog that has some really nice hats with diagonal movement in her photo gallery, in case you are interested in other (possibly better) examples.