A few more tips...

7) Follow the wooden plank roads. When you follow the plank roads, you will see more of everything, and everything in this park is worth seeing.
8) If you only have one day, see the main valley, starting at the "virgin forests" and working your way down. There are more colored pools on this side of the park, and more places to walk.
9) Don't get stuck with what you don't want, because it will probably cost you dearly. We were at a restaurant, and ordered eggplant. I come back from the bathroom, and there is a pot of soup on the table. They said they gave us this since they were out of eggplant. Fortunately, I had already seen that the soup was 168 Yuan on the menu, and sent it back, ordering a cheaper dish.
10) This park is absolutely worth visiting. I couldn't believe how beautiful and unspoiled it was. If you want to see the natural beauty of China, this is the place to go!

1) Food and drink are not readily available in the park. Every bus stop has a toilet. I only found snacks and water in the village I visited and at the transfer station.
2) The services in the park are designed to work around the tour groups. If you want to do things apart from the crowd, it is more difficult. I didn't eat lunch during lunch time, and went to the transfer station to try and get some food. Since I was there at the wrong time (3pm) all of the food and snack counters were closed. I couldn't even buy a bottle of water.
3) It takes between 1 1/2 - 2 hours to go between the park and the airport. My mother and I paid 300 yuan for a taxi. Our hotel set itup. It was worth the convenience.
4) The airplanes out of Jiuzhaigou are always late. We booked our tickets through a hostel in Chengdu. We were going to transfer at the Chengdu airport, and go straight back to Nanjing. She booked the tickets so that we would have a five hour buffer between flights. It turned out that our plane to Chengdu was over four hours late, so we just made our plane to Nanjing. This happens often enough that the people at the hostel knew.
5) Buy: a tourist sketch map (3-5 Yuan), and the small book called "A Complete Tour Guide of Jiuzhaigou, A world of Fairy Tales" (29.80 Yuan). It is the most informative book I have bought in China.
6) I paid 280 Yuan per night for a decent 4 star hotel that was an 8 Yuan taxi ride from the gate (called the Kang Ba Noble Manor). Even this was a little high. Listed prices are never true, so haggle.