Found these flights to Barcelona, Spain in May/June.
Stopovers in Shanghai (on way there) and Beijing (on return) can add to the tour experience!
Weather in Barcelona at this time of year is approximately 16c
Weather in Beijing/Shanghai is very much the same
Book with Flight Centre to get price match and $1 off
Back in 2016, Air China was no.87 in Top 100 Airlines, but should've jumped up the rankings since!
Hope this helps someone out there.
Its worth noting the times of departure aren't great (middle of the day on weekdays mostly). Also the lengthy stopover (unless entering China, in which you have to actor in the cost of Visa). Also Air China reviews aren't great, even compared to China Southern/Eastern.