Hi Rebekah (and Adam)!

I think you can find a number of places that may get you close enough; optimising things might take a bit of exploring and experience.

Much of the natural beauty of China was eaten long ago. This is a place of extremely high population pressures, and most land that can be developed/exploited already has been. Most areas of high natural beauty that still remain in China are well away from any cities. It can be hard to find jobs in such places; harder still to find one that pays much at all. A few cities score fairly well on this criterion: Hangzhou (West Lake), Suzhou (famous gardens, canals, local architecture), Qingdao (seacoast, hills, cool European architecture), Lijiang and other secondary cities in Yunnan (mountain scenery, ethnic peoples) and Guilin/Yangshuo (amazing local scenery) come to mind in the "nice to look at" category.

Getting away from hard cold is easy (although be advised that even very deep southern China can have some sharp cold snaps in winter), but getting away from pollution is virtually impossible in China. Pretty much every city here has a large industrial base. There are lots and lots of cars. High-sulfur soft coal is burned in large amounts. The use of nasty agricultural chemicals is widespread in rural areas, and there are lots of rural factories, too. There is very little meaningful environmental regulation or enforcement. If you're going to come to China, you're simply going to have to accept a certain amount of this. However, you might find places that present a pollution level you'll feel you can live with for a while. Cities on the coasts and in the mountains tend to fare better than others, and some cities such as Suzhou, while highly industrialized, don't permit the building of the dirtier sorts of factories.

Most cities of any size will have at least some foreigners, foreign comforts, and nightlife. This is of course most true in the largest cities, and the cities in the greater Shanghai area (Suzhou, Nanjing, Wuxi, Ningbo, Hangzhou, and Shanghai itself) tend to have the highest levels of this.

Finding a good school is by far the hardest challenge you will face. It's my opinion that nearly ALL schools here are dodgy in one way or another; like the pollution it's a matter of finding a level you can live with. You learn a bit with experience (sometimes the hard way, I'm afraid) but take it from me- finding a reasonably honest place to work is something that worries even long-term China veterans. What can you do? Research. Read the online reviews with an open mind. Plug into the China-based online communities (my own forum site is one such but there are others). Read contracts carefully and ask hard questions; get any negotiated contract changes appended to the contract in writing. And pray.
Oh, and one more thing: never, ever use a recruiting agent to find a teaching job in China. They tend to be even dodgier than the schools, and right now you don't really understand what a scary statement that truly is. If you can't deal directly with the school or other employer, terminate communications and walk away.

I like Xi'an...nice little city, some foreign presence, some local scene, a great wealth of history. However, it does fail on some of your criteria: It's cold up there- you're far enough north, and far enough inland, to still get a hard winter. It's also a bit dirty- some industry, lots of soft coal burned, and the surrounding area is heavy coal-mining and industrial country. There is scenic beauty in the region you can travel to, but Xian itself is not a strong contender in the looks department. A good friend of mine, who's also an admin at my site, has lived in Xian a long time and LOVES it there. However, bear in mind that this lady is a real China Warrior...she camps in Tibetan villages, goes horseback and camel riding in Qinghai and Inner Mongolia, gets into drinking contests with ethnic Tu Jia village women...that kind of stuff. Hardly the typical case!

I've taught in Suzhou, Shanghai, Beijing, Changchun, and Dalian. I've found things to both love and to hate about all of them. IMHO Suzhou is the center of the universe, but really all of this region around Shanghai can be nice. I also liked Dalian a lot, but it does get cold there despite the presence of the ocean. Beijing and Shanghai both offer delights, but can be big, expensive, and complicated to live in. Of the two I greatly prefer Shanghai. Changchun has great people and other comforts, but it is bitterly cold and dirty.

Based on my own experiences and visits, the experiences of people I know, and my own research, I especially recommend the following cities in no particular order. (These are the ones I like; there are other nice places too!)

Suzhou Jiangsu
Shanghai
Hangzhou Zhejiang
Wuxi Jiangsu
Nanjing Jiangsu
Qingdao Shandong
Dalian Liaoning
Xiamen Fujian
Kunming Yunnan
Guilin/Yangshuo Guangxi
Zhuhai Guangdong

Some cities I recommend avoiding include:

Taiyuan Shanxi (dirty, polluted, cold, backward, horrible)
Changsha Hunan (xenophobic, boring, provincial, dirty)
Chongqing (enormous urban pressures, dirty, horrid weather)
Nanchang Jiangxi (boring, provincial, dirty, backward, polluted)
Guiyang Guizhou (boring, provincial, backward, dirty, polluted)
Shijiazhuang Hebei (xenophobic, boring, provincial, dirty, polluted, backward)
Lanzhou Gansu (boring, provincial, dirty, polluted, cold)
ANY city in Anhui or Jiangxi Provinces (extremely xenophobic, backward, dirty, boring, provincial)

I'm sure all these places have their fans ready to argue with me. ;-{)

Good luck,
Raoul