Re: which sunglasses?
I wear Costas and they are the best sunglasses I have ever put on. Once I started wearing them, I would try other glasses (Oakley, Ray Ban, etc.) and they were all a distant second to Costas. Just make sure you get the 580G lenses. They are the most expensive, but definitely worth it above the plastic lenses. To tell the truth, I will wear them in low light situations also and they seem to brighten things up for me, making it easier to drive in the rain and at dusk/dawn. It is like seeing the world in HD--there are times I walk inside and forget I have them on!
To save some money, check out eBay to buy them. The retail is $249, but I've found them on eBay for around $150-$160. Hope this helps.
TJ