I bought 2 business tickets from jfk - can - pek - can -jfk last year for $2200 each on justfly with china southern and was able to book my seat on china southerns very confusing website afterwards
The only trouble i ran into i dont know id it was justflys fault or not, china southern canceled a bunch of flights from can-pek the day i arrived including mine so they put us up in 2-3 star hotel till the next day. Also on the way back from beijing to guanzghou the check in lady kept muttering about how our passport numbers werent showijf up and i would have to call justfly and make them fix it, but another check in person i guess who is more experienced clicked on a couple things and fixed it. But i would buy from justfly again just none of the extra stuff they try to sell on the side.
China southern was also great, very friendly flight attendants and great service on landing as well.
Espcially on my my flight back to jfk i was running very late due to a late arrival from singapore and i made it on time. Got through china customs and everythint in like record time Unfortunately the baggage didnt but they told me beforehand it wouldnt and i chose to get on the flight instead of rescheduling for tomorrow. My baggage came next day and was delivered straight to me with no problem.