So bottle, did I miss it or did you not mention whether you need an Rx or can buy your glasses from wider sources?
Wanderlust, there's a reason that Rx glasses fitted by an optician or other "eye doctor" store should fit you better. Inside the frame there will be tiny numbers imprinted on the temple and the nose piece. "Real" glasses are fitted by the length of the temple (side bar) and the width of the nose and the width of the front frame, three measurements. While most folks tolerate a lot of variation in the length of the temples, the fit on the nose usually feels "great" over a 1-2mm. range, and they are measured in milllimeters. The overall front width also is measured in millimeters, a 4-5mm variation really changes how they feel.
And if you need an Rx, centering the lenses to match your pupils isn't always done properly--since time is money. I joke with my optician that one day I'll get my ears fixed with plastic surgery so he won't have to align the frames to fit them properly. Most people have slight differences in their ears, requiring some "frame adjustment" to make them sit straight. Some folks do this themselves, others just don't notice the world is a bit crooked.
Rx sunglasses give you way less choice than the plano (no Rx) ones but I've accumulated a variety of both over the years. Some nice gold-flashed glacier glasses with eye cups, that totally eliminate glare. Somehow you get used to the color (the gold totally blocks infrared, the glass blocks UV) and the world looks odd when you take them off. A less technical pair with thicker glass, gold flashed from Nikon. I like glass lenses because they just don't scratch like plastic does.
Got a pair of "pinkish" Serengettis as well, great driving glasses, great extra contrast for scanning distant things, but plastic (I'm afraid the salt
will chew into them eventually) and not as dark. I'm more likely to use them in spinrg/fall when the sun isn't as harsh at midday.
Among the others are some vintage "Cool Ray Polaroid" made by Polaroid back in the day. They're not as dark, they're way cheaper (and flimsier) but the polaroid lense certainly do cut glare better. Great for fisherman...but glare off the water doesn't bother me in general, if the lenses are dark enough to cut the sundogs down to size.
I find that glasses dark enough to really cut glaring noonday sun, are too dark early/late in the day. But if I wear really dark lenses for most of the day, it makes a huge difference in my night vision.
And then there's the pair of inexpensive dual-gradient mirrored glass ones I found on the boat one day. (Mirrored heavier top and bottom, not in the middle.) Never have figured out who they belong to, so they are there for "guest" use.<G>