Alternating rows of proper gauge with very loose gauge in simple single crochet is a very interesting way to create a lacy pattern and drape. You could achieve this by switching hook size with the same yarn, or, as I did in this sweater, alternating weights of yarn with the same sized hook.

The thicker (ribbon) yarn uses the proper sized hook (H/8), and I used a laceweight mohair held together with a carryalong (thinner than laceweight) sequined yarn for the alternating row, but I continued with the same hook. The finished fabric, after blocking, has lots of negative space and really opens up the pattern. It looks like a stitch pattern rather than just rows of easy-peasy single crochet. And the added sparkle of sequined yarn is just plain fun!