Chengdu to Jiuzaigou on hired Car

Hi there,
We are a group of 4 adults and 5 children (two age 9, two age 14 and one age 15) that want to travel from Chengdu to Jiuzaigou and Huanglong. What are the best ways to travel, is it by public bus or hired car? How much per day when we want to hire car with the capacity of those 9 people?
Thanks for your answers.