Lufthansa and Swiss are both running a companion special for first class flights with departure from Athens. If you travel to one of the two destinations in China (or to Hong Kong) with another person, you can get tickets for prices starting at only €2,499. That’s what you’d typically pay for a seat in business class!
Update
Hong Kong as a destination is possible as well. You can just ignore the pre-selection on the landing pages and look for flights to Hong Kong for 2 persons in first class and the offer will appear.
Both airlines offer the same three destinations: Beijing, Shanghai (and Hong Kong). Also, the pricing is the same. So your choice will be a matter of which product you prefer.

Comments (2)
Where can I book just the night from saturday to sunday, do not want to stay 6 nights
Hi Thorsten, the minimum stay from Saturday to Sunday refers to the carriers’ fare rules. However, these flights may have sold out already. All available connections can be found and booked via the airline’s website.