Hmmm, that's a tough one. I feel like I could have stayed in Chengdu forever. Although the food is just spicy, I just enjoyed the city and its structure. Just a drive away from pandas in Bifengxia (and also the beautiful scenery in that gorge!) and also Emei Shan which I would love to see again since it was too brief, and the monumental statue at the top was partially hidden in clouds. I also absolutely loved Guilin, which has beautiful scenery all around including Yangshuo.
I don't think there's any city I wouldn't return to that I've visited, but I don't think I'd ever miss not going back to Expo in Shanghai. It was intense! I learned to appreciate civilized lines though.
I'll be heading to Beijing for 2 months in order to study Mandarin, and ~ 4 months later will be heading to Shanghai for a semester abroad, which will be my last hopefully, and I can stay for a while and get them to mail my diploma.
I've tried the baijiu in Beijing last time I was there at a local friend's birthday party, a little too intense for me! But I'll have a beer or two!