I made my first Amy Butler bag a few years ago - it was a bag to carry my yoga/pilates mat to classes. I made it from this turquoise AB fabric which I really liked.
I recently joined a yoga studio and have needed a bag (other than plastic grocery bags!) to carry my clothes. This is what I came up with (my first time working with oilcloth - I like it so much better than clear plastic vinyl! it sews amazingly well).
With an extra (waterproof) oilcloth section to divide my clothes from the day away from my yoga clothes:
Velcro-ed pocket on the outside for my keys: