I did option 1 (Chengdu Panda Breeding Center) some time ago. I hired a guide once inside since I don't speak Chinese, and didn't cost too much if I recall. Most other tourists did unguided tours. However, there were some tourists who followed us around and tried to listen to the guide in English, for free, and even asked the guide their own questions. Needless to say, the guide was quite annoyed.

Moral of the story: please be considerate and don't mooch off other paying tourists. It will be awkward for everyone.