Compared to most, I've got a pretty big head. I found a pair of safety glasses at Northern Tool for about $3 (see them
here, or
here, or
here) that fit me well--they flex to keep the glasses from pinching my head, which makes them infinitely more comfortable for wearing over extended periods (read: most of the final week before ship, regionals, etc.).
At IRI I was talking with Greg Needel, who happens to wear a pair of DeWalt safety glasses for some strange reason (it's almost like he works for them!). It turns out that mine are a knockoff of the DeWalt glasses; both pairs fit my head great.
I've worn smaller safety glasses, and they hurt after a day of coaching. Of course, I don't want to
wind up like Carol, so I grin and bear it. Sometimes, students I've worked with have been less disciplined--therefore, I take no chances with going for uncomfortable ones.
Moral of the story:
-Make sure the glasses are ANSI approved.
-Make sure the glasses are legal under the 2009 FRC rules.
-Make sure you can wear them for twelve hours at a time--some members of your team will at a regional.