Go with a nice pair of WileyX sunglasses. I've got the SG-1 and really like them. All the sunglasses and replacement parts have National Stock Numbers, so your supply sergeant can order parts as they break. The complete list of NSNs are on the WileyX web site. The only gripe I have, and have seen from others, is when they are sealed against your face with the headband strap, they tend to fog up. The seal is TOO GOOD. I haven't tried any of the commercial anti-fog liquids so I can't say if they would work or not. The lenses are sufficiently dark the bad guys (or good guys) can't see where you are looking, or if you are asleep.
When I was in Baghdad last year, I had several locals wanting to look at my WileyX sunglasses. They thought they were special X-ray glasses and that I could see through their buildings and clothes. I guess it was a case of watching one too many James Bond movies, or overestimating our technology. This mikght be something you can use to your advantage while on patrol. I had even heard of one bright soldier using his Inova LED clip light to "scan" a person, then push the backlight button on his watch to determine the guy in question was hiding something or lying. The guy got nervous and confessed. A bit off topic, but be sure to use all your gadgets to your advantage and be creative; you never know what might just work. Stay safe,
RadarGreg