Help! Kunming, Beijing, Xi'an, or Taipei?

Hi! I'm a university student planning on studying abroad to China next spring (in 2011), and I was hoping to get a little advice from all of you wonderful people! My university has study abroad options in Kunming, Beijing, Xi'an, and Taipei (in Taiwan, not China), and I can't decide which option to pursue! Right now, I do have a slight preference for Kunming, but that is mostly because that is the only program with a homestay option. Since I really want to become fully immersed in Chinese culture, I think the homestay would be the best setup for me! But what do all of you think? Have any of you ever been to these cities? Any input would be very much appreciated!