In general, I prefer plastic, oversized sunglasses over aviators. The weight is more evenly distributed and the more oversized they are, the more sun protection for the eye area! They’re also great for sleeping on a plane. In my opinion, sunglasses are one of the worst things to forget on a trip.
I’ve been into tortoise rimmed shades of late. During the fall, I got these Marc by Marc Jacobs sunglasses in “Havana” brown (style 213/S) when Shopbop had a sitewide promotion. I have a typical Asian face and Marc by Marc Jacobs (as well as Michael Kors and Forever 21) typically do not disappoint. MBMJ is extremely reasonably priced for the quality.

This style has been out for a while. They are currently sold out at Shopbop and Saks (but I have seen them popback on Shopbop), but available through third party sellers at Amazon.
A funkier rendition is available from Australian designer, Karen Walker (no, not the character from Will & Grace) and made very popular by Blair of Atlantic-Pacific.

Number One ($250), Harvest ($280)
Eaton Trading Company currently has 30% off sitewide including Karen Walker (limited styles), Clare Vivier, and Illesteva.
For more wallet friendly styles, check out Forever 21 (and I snuck another MBMJ in). Although I don’t expect them to last forever, they often do. They’re an easy and cheap way to get through a trend.
F7828 Oversized Round Sunglasses ($5.80), F0365 Round Frame Sunglasses ($5.80)
F6267 Cat-Eye Sunglasses ($5.80), F0339 Round Frame Sunglasses ($5.80)
F3891 Round Sunglasses ($5.80), MBMJ 57mm Sunglasses ($110)
Images from Forever 21, Nordstrom, Karen Walker, and Shopbop.