What he said, or you could join the Army and get 2 free pairs of BCGs, toughest specs you'll ever own. I think you could probably talk them into throwing in a bonus pair of prescrition gas mask inserts if you talk fast enough.
Seriously though, the ti glasses, or the flex frame alloy glasses will take a lickin'. I had a pair sucker punched clean off of my head. I woke up at the last second and slipped most of the punch, he caught a little bit of cheekbone and a whole lotta glasses. Didn't even phases them, a quick thinking buddy (though his priorities are a little suspect) snatched them up off the sidewalk almost immediately and returned them to me post discussion. Not a bend, wiggle or scratch on them. Worth the extra $.
I'm also a fan of cable temples, the type that wrap around and under your ear instead of just having a downward bend. Hard to find though, I wound up having my specs fitted with them later through a local shop who can do that sort of thing.