I'm a little bit overwhelmed by options, so I'm hoping someone can point me in the right direction.
My morning commute to the office is on foot, so I need to schlepp my stuff with me, but want to arrive at work looking halfway professional, not like I'm going camping. I need a bag that will hold:
* A medium-size purse
* Lunch
* Shoes
* An iPad
* A change of clothes for my after-work yoga class
And, optionally, if there was a way to attach a yoga mat, so much the better, though in wet or snowy weather, I'd be carrying it in its own bag anyway to keep it dry.
What are my best choices?

