门票 is about 250元 for 3 days. There are two entrances (that I know) from 张家界 city: one is known as 森林公园, the other is in 武陵源 city. In both cases, you take a bus from the 张家界 city bus station, costing about 30 元。
I recommend staying inside 张家界 park once you enter the park because it takes at least two hours go get to 张家界 park from 张家界 city (bus trip, wait in line for the lift, and wait for bus once inside 张家界 park). You can have your luggage sent to your 客栈 inside 张家界 park.
There are a lot of 客栈s inside 张家界 park. They are simple, and inexpensive. So keep your expectations low.
Once you are inside 张家界 park, you can decide where to go by consulting with your map, or ask some one for advice. Remember, 张家界 park is VERY big, much bigger than 黄山。