So I've never owned a pair of sunglasses before because I'm not a sunglasses kinda guy but I took a shot with these (From SAC, black/grey non-polarized, only about $40 including shipping). Being a noob with sunglasses, I don't really know my face size but I'll guess medium, maybe medium/small (5'9 150 lbs) and it's a good fit. While the glasses are on, there's no slipping even when bending over which is surprising because there are no nose-/temple-grips. When you have them on top of your head (bro-status, haha), they'll move around a little but if you have a bigger head then you'll be alright. As for the style, the lenses are pretty big considering my face size but the square frame makes it look nice. Not only do the lenses provide excellent cover, I found the wide ear pieces (whatever it's called, arm? The other end of the hinge after the lenses) conveniently block out the sun from the periphery too; it's not like you're always looking in the direction of the sun, y'know? So I like the look and the function, I get compliments from friends and ladies alike. Durability-wise, I've had these things for over a year and only a few minor scratches; they still look great. In fact, the only reason why the scratches are there is because I'm pretty careless with these. I lost the pouch for them so I just leave them wherever; I'll throw them in my backpack (it has a shitty, likely abrasive sunglasses pocket) or hang one of the earpieces from my front pocket when the sun's not out. Loved these glasses so much I started getting other pairs; now I have a pair of Oakley M-frames (so ugly you can only wear them for physical activity, haha) and a pair of classic Ray-Ban aviators. Price aside, I would choose these Smith's over my other pairs any day. Attached is a pic I took with them to give you all a better idea.
Edit: And I should mention while my Ray-Ban aviators leave painful and obvious marks from the nose piece, these Smith haven't hurt me one bit nor left any mark even when wearing them for hours straight.