you should for sure try to get some polarized glasses, I have been using free sunglasses forever and the polarized glasses are really so much better, I have both of these and like them about equally so...
Check out tints: http://www.tintswear.com/shop
They're $35 and have bamboo arms which is cool, they're also extremely light. I use these for walking around campus, or driving.
Also look at the planks clothing sunglasses: http://www.planksclothing.com/shop/planks-vision.html#vision-sunglasses
they're $54 and seem to fit a little better and are bit more durable, but obviously more expensive. I use these ones when I'm hiking or skinning or skiing, they seem to stay on my face a bit better.