For the Minimalist (or Ninja Assassin):
If you are looking for some basic pieces, these will be your best friend. I love them for more intense workouts, like running, and usually wear them on their own (gotta love that sleek all black ninja assassin look) - but sometimes I like to add a pop of color to this outfit by layering a fun tank or hoodie over it.
For the Cool Kid:
There's nothing you can't do in a white tee and a good pair of skinny yoga pants (well unless we're talking of a black tie event), whether it's yoga or dancing (or outdoor shopping) this combination always looks great.
...but yes this classic look might also be a little too plain for some of us, so lets add some fashion magic and stir:
Just pair that white tee with some fun sweatpants, or wear your yoga pants with a printed tee. Personally I LOVE Wildfox tees, and yes I know they are a little bit pricey (okay total splurge items), but they are the softest, comfiest and coolest shirts you can get - so they are definitely worth the money! But of course there are other stores like H&M that sell similar styles, and then there's always the option to hit some thrift stores and look for vintage pieces.
For the Material Girl:
This post wouldn't be complete without some Juicy pieces. Some might consider them tacky, but If you go for classic colors and styles (= avoid neons, pastels, and rhinestones) these sweats are anything but tacky, and there are only few sweatpants that are as flattering as the Juicy Couture ones...Just never wear them with UGGs (unless you're practicing yoga in your bedroom)