Could you be more specific? Is the program itself 4 weeks, or your travel time? If the program and travel is four weeks, you should be fine. Otherwise, you're spoiled for places. If in Kunming and Lijiang, why not try some other places in Yunnan (Dali, Xishuangbanna) or check out Chegdu/Chongqing? You could also try to get into Tibet (Lhasa) for a few days. I'm a huge fan of Xinjiang particularly Kashgar. Guilin and Yangshuo are also possibilities. I haven't been to any (save for Xinjiang, Xi'an, Beijing and Shanghai - of the places you mentioned) and need to get on it pronto.

But my main point is that you are spoiled for places to visit and see in China if you have the time. I don't know how sciency and tech that places in China are, though, since I'm not much of a tech geek and didn't actively search for it. I guess you could always check out a few of the electronics markets here in HKG or Zhongguancun in Beijing just to get an idea how tech and electronics shopping for most geeks/average people is. Very different from back home in the US.