I've looked through some of the threads in this form. Some suggest purchasing through ctrip/elong while others suggest getting the walk-up fare. I would like to solicit your suggestions about where and when we should book our tickets to get the best price. My family and I are traveling in the second week of January, and we can commit to the dates and times now.

The first flight my family and I are taking is: KWE-PEK (Guiyang-Beijing). We're pretty much restricted to the last flight out of the day on Hainan Airlines which costs CNY$870++ (ctrip). We believe this fare will slightly drop to CNY$690++ so we will hold off to purchase it.

The second flight is a bit more tricky. We are taking a weekday evening flight from PEK-CAN (Beijing-Guangzhou). Ctrip lists the cheapest fare as CNY$1190++, and it does not appear these fares go down as the departure date becomes closer. China Southern's (CZ) website lists a promotional price for CNY$700++ but their website does not allow us to book it using a credit card issued with a US-bank. Air China's (CA) website lists a price of CNY$510++, but I haven't tried going all the way through with the booking process (supposedly they take Visa).

EDIT: I tried booking through Air China's site but the price went up after I selected more than 1 person (we have 5 adults + 1 baby traveling).