Shape: Think rectangle is your only option? Think again! The one time I visited a high-end yoga studio I was shocked to find all the mats were large cushy ovals. Corners harsh your mellow, I guess. Also available are circles, squares and “yoga sheets” – mats large enough that no matter which way you come crashing out of your inversion, you’ll still land on mat. Although you should know that the larger your mat, the more territorial you appear. Floor space is at a premium; are you a good sharer?