My biggest regret in 3 years is to not be able to visit my ancestral homeland of China for more than 3 days. I will be taking part in a 72 hr transit visa as I visit next week on my way to Thailand, this will make my trip very rushed and unenjoyable. I should of applied for a visa at the Chinese embassy while I lived in Washington DC, stupid me! I would of had a visa that was good for 10 years, and would continue to be good even with a new passport as you are allowed to bring your visa in your expired passport to count towards your entries in the new one.
Better yet, the wife of a good O-5 friend has started a company: http://www.okichinatour.com/ that will get you visa in as little as 10 days. She offers tours of Zhangjiajie National Park! Which is picture perfect sightseeing. Be sure to check out her site, and be sure to get your visa while stateside!
Edit: Thank you Nathan for mentioning that there is now a 6 day visa free stay in China while in transit.