Do not wear any tinted lenses at night. Period. It is simply not safe, even if it does make you feel better. It makes the headlights more comfortable, but hurts your ability to see anything else that isn't lit. Just don't do it.
As for sunglasses the rest of the time... Yellow lenses are fine for the gray days as Al mentioned. I did some research on the effect of yellow lenses when I was in grad school and they don't help you see better on the gray days. Whether you test visual acuity or contrast sensitivity, there is no evidence they help. OTOH, pilots invariably prefer them and when I flew I wore an amber photochromic lens simply because I liked it despite the research which said it didn't help. The preference is simply psychological, which is fine by me.
For general wear, your best bet is a neutral gray lens. It won't distort color vision and provides the protection that is helpful. Above all, buy lenses that are 100% UV absorptive in both the A and B UV bands and wear them when in the sun. UV exposure hastens cataract formation and increases the risk of macular degeneration. I always tell my patients to protect their eyes from the sun as they do their skin. So wear sunglasses and a hat.
Sunglasses that provide that UV protection don't have to be expensive. It is cheap to make 100% UV lenses and unless you are buying them at a Podunk gas station somewhere, in the US if they are labeled as 100% UV absorptive they likely are.
It is not cheap to make non-prescription (plano) sunglass lenses that are free of optical distortion. This is where often the inexpensive sunglasses fall down. Take the lenses and look at a grid pattern at reading distance while holding the lenses about 8 inches away from your face. Slowly pass the lenses back and forth over the grid and look for any distortion in the grid lines. Most often you may find it near the edges of the lens. High quality lenses will tend to be uniformly good in this respect. Cheap ones will be hit and miss. So if you can examine a few, you should be able to find a pair that are pretty good.
I don't know much, but this is one area that I actually know what I'm talking about for a change.[/QUOTE
As a skier of some skill, I can attest to the fact that yellow lenses worn on an overcast day are essential. Without them or when wearing gray lenses a skier will absolutely not see bumps or depressions in the terrain making skiing at any speed above very slow treacherous. As for boating I'm not sure whether yellow is of any value on an overcast day.
