In my opinion, gray tinted sunglasses are suitable for all occasions. As we all know, grey is a popular neutral tint color which allow wearers to see the purest form of the objects, so grey tinted sunglasses won't cause vision distortion. What's more, gray tinted sunglasses can help reduce the glare and weaken the brightness of the sunlight. They are good for outdoor activities and driving. Brown tinted sunglasses are also popular with many people. I think brown sunglasses can also be used for all occasions.
As far as I concerned, to find a pair of sunglass that is suitable for all occasions is wise and possible. I have several suggestions. In the first place, you can choose some sunglasses that are in the basic style, for they are more universal and worthwhile in life than the most fashionable ones. Secondly, you should pick some sunglasses in regular colors and avoid those ones in bright colors. For example, you can choose black and gray ones. Because they're tieless colors and easy to match our dressing. At last, you can choose some simply-designed ones, which are not so easily out of fashion and you can wear them for a longer time.