Living in China and being married to a Chinese woman, being able to put the culture, politics, etc. into context is important to me. This means I should read and research, of course, but so many of these events - especially from a Chinese perspective (and especially recently) - are so contorted or misrepresented as to be worse than reading nothing in some cases (e.g., the number of deaths from the Nanjing Massacre seem to rise every time it's mentioned). With that, I turn to /r/askhistorians to hopefully get some more reputable, comprehensive - and if it's not too much to ask - compelling sources.
Specific things that I'm very interested in:
How China and Japan's relationship developed between late 19th century and early/mid 20th century. I imagine books about the Nanjing Massacre and the war would be a huge help.
An objective inquiry into Mao's rise to power and/or an analysis of his policies and their immediate (and possibly long-term) effects on China. There's one well-known (infamous?) book I read about Mao (can't remember the title), but it seemed to somehow manage an overly-critical, almost sarcastic tone that didn't sit well with me. I don't like Mao, but I wanted an objective book, which this was not.
(This one's slightly out of the scope of my original question, but still something I'm interested in) China's historical claims over certain territories, especially Hong Kong (in this case, how and for what reasons it transferred hands to and from the British), Tibet, and Upper Mongolia (or whatever the name of the territory that China claims Russia took from them). I'm not interested in the Diaoyu Islands because (and correct me if I'm wrong) it's basically a farce at this point (and I'm tired of hearing about it, honestly). Also, if there's more to Taiwan than "Chinese people live there now," that would be interesting, as well.
Of course, if anyone here is willing to offer up a good response to any of these topics, I'd love to read about it.
AskHistorians has a pretty good book list for China that would probably be a good place to start. As for your question about Hong Kong, I would recommend A Modern History of Hong Kong by John Carroll, which is pretty comprehensive and is written by the leading scholar, in my opinion, of Hong Kong history. There's also A Modern History of Hong Kong by Steve Tsang which is also pretty good, but it has a bit of a British perspective, so I prefer Carroll's, who tries to give Hong Kong its own place in history. I can also give you a bit of an somewhat lengthy overview of the transfer of Hong Kong to and from the British.
The British acquired Hong Kong through the first Opium War in 1839-42. The British started this war because they felt that the only trade port with China, Canton, was restrictive, corrupt, and inefficient. Because the Beijing government controlled trade through fines and documentation, the British increasingly felt that free trade was necessary to rid themselves of these deficiencies. This was especially true for the opium trade, which was outlawed by the Qing government at the time, and the only way for the British to make money off the vast amounts of opium that they were growing in India was to smuggle it in, further encouraging corruption. The British wanted free trade but more importantly, to openly sell their opium. Once the British won, they opened several port cities along China's coast for free trade and acquired Hong Kong. The primary reasons for acquiring Hong Kong in particular were because it had deep water harbors that protected it from harsh weather and the British believed that they could profit greatly by having their own port near the coast of China instead trading at the newly opened ports. Many British officials actually opposed the acquisition of Hong Kong, because the island "was a barren rock with hardly a house upon it," and thinking that merchants would just trade in Shanghai or Macau, which was the case during the colony's early years. But as we know, this changes later.
As to how China got Hong Kong back, this was a bit of a fluke on the British side. During the Convention of Peking in 1899, China leased the New Territories (a sizable chunk on the mainland between Victoria Harbor and the Shenzhen River). The reasoning for this lease was because the British wanted a buffer zone to protect Hong Kong, not necessarily from China, but from the growing Russian and Japanese powers. The British wanted a permanent cessation, but the chief negotiator assumed that this 99 year lease would be permanent. The Chinese were reluctant to hand it over, but wanted to do it quickly and without much fanfare to prevent other powers from using it as a pretext to gain more concessions.
Because of this lease, China had a legitimate claim to take back Hong Kong in 1997. Even though the lease only applied to the New Territories, by the time 1997 rolled around, the island and the New Territories were so intricately linked that it would have been impractical to separate them. Moreover, British power had declined by then and could not defend Hong Kong whereas China had grown into a major world power. China was also eager to take back Hong Kong and recover face from its "century of shame." So while the people of Hong Kong preferred to stay under British rule, the British had no way of keeping it and both the Chinese and the British wanted the dispute to be solved with as little bloodshed as possible. There are also some relevant posts that have discussed why the Chinese didn't try to invade Hong Kong forcefully.
Another source I used in this post relating to the Canton Delta trade system was Paul Van Dyke's The Canton Trade: Life and Enterprise on the Canton Coast: 1700-1845.
Few books from a Tibetan and Western perspective.
A Political History of Tibet - Tsepon Shakabpa
Dragon in the Land of Snows - Tsering Shakya
A History of Modern Tibet - Melvyn Goldstein
Tibet: A History - Sam Van Schaik
Have you talked about Tibet with your Chinese wife? What was her response?