Hi
There is no direct flight from Beijing to Jiuzhaigou. You have to transfer at Chengdu. The flight from Beijing to Chengdu takes 2 hours and 40minutes. The economy fare is CNY1440. The flight from Chengdu to Jiuzhaigou takes 45 minutes. The economy fare is CNY980.
Jiuzhaigou is high elevational region. You should prepare some medicine just in case.

Bret,
Thank you for the information. Should we join a tour? is that safe to go without a tour?

I would often choose to tour on my own, as there is more freedom. But to ensure a pleasant tour, a lot of preparation work must be done. You must first study the best route you should follow. Joining a tour will save you time and energy as they make arrangement for you yet with less freedom. That is my feeling. you weigh and make a choice. Good luck!

This might be way too late but there are direct flights from Beijing to Jiuzhaigou as of autumn 2009. Check the schedule on ctrip.com or elong.net or one of those sites.
I would advise against booking a tour. Do your research, find accommodation on line and go that way.

Thanks for yr prompt reply.. I love the cold weather..looking forward to my vacation... Singapore is so hot...now....