First of all, it wouldn't be fair to others that I've recently lambasted to not tell you that we're talking about "Air China".

In the event that fares were the same, I'd book directly with CA if I cared about the extra 4% that ctrip will tack on (assuming foreign credit card), but since ctrip has bailed me out of many jams, I'm usually happy to pay their surcharge.

Unfortunately, even with a ctrip booking, you can't simply go to the next gate and board that flight, but they can help you craft a viable walk to and from the lobby that will get you on that flight.