My friend and I have just had a big fight about would anyone hire a Chinese interpreter when he or she visits or travels to China, provided that he or she cannot speak Chinese? She said no one would do such a thing since they travel to a Country because they want to know more about the culture and life style of that Country not it's language. But I considered it the other way round that because the travellers want to know more about the Country they are visiting,they need interpreter(s). Without listening to and talking to local people by themselves,how can they be so sure they really understand that Country. They just see things around but it is hard to fully sense the essence of that Country. I always think that without any verbal connection to local people their feeling about their trip cannot be full.
Visitors to China will fall into 2 large groups.
1. Those that prefer being in a group when visiting the Great Wall, Terracotta Warriors, 3 Gorges Dam, etc. Most of those over 50 yrs old will most likely be in this category. The language problem is solved when traveling with a group. Unless that interpreter cannot speak understandable English! (or any other language needed).
2. Those visitors that prefer independent travel.
Many independent travelers are on a budget and cannot afford an interpreter. That leaves a small group of visitors that travel independently and can afford and want their own interpreter. There is a need for interpreters in China, but I don't think most visitors to China will hire one.
I live in China, and have done for 4 years now. Over the time I have lived here I have learned Mandarin, and can now hold reasonable conversations with most locals. In my early days, I never had an interpreter, but I always carried around a phrase book or a dictionary which aided understanding in both directions. Now you can get a very useful app on your iPhone!
However, even now when we visit places where I feel I need an in depth explanation of cultural or historical significance I always look for a guide who speaks English, as opposed to an interpreter. We had a tourguide take us through the Kunming Stone Forest, as my Chinese is certainly not up to having discussions about karst rock or relocating villagers after the Stone Forest became recognised as a World Heritage site, and I didn't want to become lost in the park (with two small kids in tow), so having a guide served a double purpose. Recently I went on a tour to a tea plantation, and again I wouldn't have the vocabulary to discuss the finer sides of tea, so enjoyed having an English speaking guide.
Tourguides here are often students, who have an amazing depth of knowledge about the site they are talking about (e.g. Forbidden City Beijing, Shanghai Museum) and their English is excellent. Often you only need to pay them about 50rmb (GBP5) for a tour (sometimes you also need to pay their entry into the site, but sometimes they get you a discount for your entry) and in most cases the tour lasts as long as you want. Yes, there are occasionally stories about being fleeced, etc, but I think on the whole a tour guide here is a benefit, especially if there is something significant or specific you want to know about.
You say about connection to local people, but if you learn a few phrases like thank you, hello, good bye and delicious/yummy - it goes a long way too!!! Have a great trip!! And if you want any specific info let me know!!