You don't need a tour, and it would be horrible to be on one inside the park. They aren't any great bargain, either. Instead do this:
1) Book your flights XIY-JZH and JZH-CTU. Use www.travelzen.com, www.ctrip.com or www.elong.net. The first one doesn't charge an extra 3% for using a foreign credit card.
2) Book your hotel at Jiuzhaigou. You can also use ctrip or elong for this. www.sinotrip.com is also reliable. The best location is a hotel in Pengfeng, since everything there is within walking distance of the park entrance. Ask if the hotel will do an airport pickup and how much it will be. If it's RMB 250 or less (total for the car, not per person), take it. Otherwise, there will be plenty of taxis at the airport--all they need is a hotel/address name in Chinese, which you can print off the internet.
3) Don't worry about setting up a return ride back to the airport. That is best done in Jiuzhaigou, the day before you need to go back. There are tons of taxis around that will take you.
1) and 2) will take a total of about 3-4 hours of your time to do a little research and make the bookings. Then once in Jiuzhaigou, you just get to the ticket office and buy your tickets yourself. There are plenty of eateries and supermarkets/shops etc. for anything you might need.