You should stay in Wulingyuan district instead of Yongding district because most of the tourist attractions (Zhangjiajie National Forest Park, Baofeng Lake, Yellow Dragon Cave, Grand Canyon and Glass Bridge etc.) are located in Wulingyuan district. This can help you save a lot of time and money for the transport.
Tianmen Mountain, Zhangjiajie Folk Custom Park and the Zhangjiajie Hehua Airport are in Yongding district. You can see the Wulingyuan district's attractions ( 1-3 days) first and then see the Yongding district's attraction (1 day is enough for Tianmen Mountain + Zhangjiajie Folk Custom Park + Airport transfer).
Please note that the star-rated hotels in Zhangjiajie might not be up to the standard of those in the famous tourist cities like Beijing, Xi'an, Shanghai, Chengdu and Guilin. Most hotels in Zhangjiajie opened over 10 years ago and have not undergone renovation, so the facilities might not be very new. For example, 4-star hotels (first class) in Zhangjiajie might only compare to economy standard hotels (3-star) in cities like Shanghai. Breakfast at a 4-star hotel in Zhangjiajie is very basic. At 5-star hotels breakfast is usually Chinese style mixed with some western choices. We suggest you bring your own toiletries and towel.
Zhangjiajie features a lot of boutique inns. Some inns are even more expensive than the deluxe hotel. Most of the inns only offer Chinese breakfast, don't offer Western style breakfast. If you find a special stay, we suggest trying the ethnic style inn.
Please also note that tourists cannot stay overnight in Zhangjiajie National Forest Park. All the family hotels and inns were relocated outside the park in 2017.