I have a small, very small head. I also detest wearing hats (make my head hurt, hat hair, sweat), but I bought a long visored Nike cap at the LRS and it fits me perfectly. The visor is so long, I feel like I am wearing an awning. It's very light weight, but not really vented.
I understand wearing a hat while running, but why do I see women around town, wearing these caps as they are out and about? And, they're always getting into an Escalade .
Don't get me started on men who wear hats as a fashion accessory.