CTrip is China’s preeminent online travel service and I’ve recently used them to book airline tickets to Chengdu. Their website is all in English, takes international credit cards and is very easy to use. If you’re in China, you can call them and helpful English-speaking staff can book tickets for you quickly. In fact, I just booked 3 tickets to Taiyuan for my family over Labor Day (May 1) and the transaction was completed in less than ten minutes. Fantastic!