Hainan Airlines, one of the top 5 star airlines in the world is offering flights to Sanya, China for $587. Sanya is supposedly the Hawaii of China. These flights are a few hundred dollar more normally however I've found Air China offering similar flights for $125 more. Dates are in March.
However, the big + of Hainan is that they'll put you up in free accommodation for stopovers bigger than 6 hours. So potentially you can score 2 nights free hotels which allows you to check out Shenzen for the day. Hainan's Transfer Accommodation Service
Easiest way is to go onto Hainan's website, pick some days and then have a look at their grid calendar. Screenshot. Then plug these into Skyscanner to get a slightly cheaper flight.