I'm going to break this trip report down into city-by-city coverage, beginning with Shanghai, which is where this grand trip all started. So far I've been to Shanghai, Dalian, Harbin, and Mudanjiang. I still have Beijing, Chengdu, and Chongqing left to see. To sum up my trip so far: China is a very unique and interesting place, but this country sure is hell is not for everybody, especially the less-traveled. It's very much a love-hate kinda country that will have you riding in an emotional roller coaster full of ups and downs. Okay, let's get started with Shanghai:
Shanghai 上海

My first impression of Shanghai was that it's a massive city that's somewhat internationalized (at least "internationalized" to Chinese standards, which is generally further behind many other Asian countries). The buildings are super tall and modern, and the city seemed surprisingly clean. One of the first things I noticed was how clean and wide the sidewalks are. Bangkok's sidewalks are narrow and filled with discarded food and rubbish. Walking around the city by foot wasn't too difficult. Far more pleasant than Bangkok to say the least.
The weather was pleasantly cool during my 3-day stay in Shanghai (which was in mid-March). All I wore was pants, a T-shirt, and a light jacket. As for the air, it didn't seem all that dirty while I was there. The air looked slightly hazy, but I could still see some clouds and blue. On the other hand, after my first day in Shanghai, I developed what I like to call "China throat." This is when your throat is constantly filled with phlegm and you need to regularly cough or spit to clear your throat. I hadn't felt that feeling in over two years (that last time being when I lived in Dalian in 2012). That said, there is definitely something about China that messes with one's immune system.
The food in Shanghai didn't really stand out to me, but I noticed one striking difference between China and Thailand in regards to food. Cheap little restaurants can be found practically anywhere and everywhere in China, but if one wants cheap food in Thailand (or at least Bangkok), one tends to gravitate towards street food. Sure, there are plenty of cheap restaurants in Bangkok too, but no where near the quantity or to the extent of most of China. Cozy little restaurants in Bangkok sometimes have a tendency to be overpriced, whereas little restaurants in China are almost always very cheap. If you want cheap, good food in Thailand, stick to street food and food courts. If you want cheap, good food in China, stick to the small family-owned restaurants. I totally disagree with the old traveling adage: "if many people are eating somewhere, that generally means its a safe place with good food to eat." Sure, those places may be safe, but if Asia has proved anything to me, it's that really popular places are almost never the places with the best food. Not even close. Asians far too often choose restaurants based on pretentiousness and "good face," not great value and truly good food.

Some good news: there are practically no street sellers on the streets of Shanghai or many other Chinese cities! One of my biggest complaints about Bangkok is that there's so much bullshit lining its sidewalks, most of which is food sellers and people selling useless junk. In China, there are people called "Chengguan" (城管), and their primary job is to keep sidewalks clear of unlicensed sellers. The Chengguan have a bad reputation for often using excessive force, but I have to admit they get the job done. Back to food - local Shanghai cuisine is nothing to rave about, but with Shanghai being a more international city, that means it's pretty easy to find Chinese food from other regions (Guangdong, Sichuan, the northeast, etc). There's also way more international cuisine available in Shanghai than in most other Chinese cities. For most of my meals (when I ate Chinese food), I only paid about 10 to 20 RMB, but bear in mind I was mostly eating at little rinky-dink restaurants, which is just fine by me.
Walking around Shanghai, there was plenty of eye candy to be found. When I used the "Look Around" feature on WeChat, I had a steady flow of at least semi-attractive girls trying to add me to their WeChat contact lists. I found Shanghai fashion to be pretty decent, but I have to admit that Bangkok fashion is more colorful and to my tastes. However, all things considered, I find the average Chinese chick to be way more attractive than the average Thai chick. Call me biased because I have a Chinese girlfriend, but I think Chinese women are almost as good as it gets when it comes to Asian women. If you're looking for a serious girlfriend, I don't think Shanghai would be the ideal place to go, mostly due to the reputation of Shanghai girls being bad girlfriends. However, if you're just looking to play around, I imagine Shanghai would be an excellent place for just that. Surely good girlfriends can be found there too.

Now for the bad - Shanghai is super-crowded, and this is no more apparent than on the subway. Riding the subway at pretty much any time of the day or night is a complete nightmare. And I used to think Bangkok's BTS skytrain is crowded - it's got nothing on Shanghai's subway! And remember, this is China, which means you'll be riding with other Chinese passengers. Mainlanders have a well-deserved reputation for being rude, aggressive, and pushy. Be prepared to be pushed, and I mean pushed HARD, several times while riding the subway. There are many times where I thought I was gonna fall to the ground from being pushed so hard. The subway system is also very cheap in Shanghai, which means there's some good and bad news. The good news is you save money, but the bad news is this cheapness allows people from all classes to ride the subway system - hence the mega-crowding. And I hate to say it, but many Chinese people on buses and in the subway smell very bad. Get ready to constantly smell unwashed clothes, bad breath, and many other foul smells while in China - they are everywhere. China is quite a crude country, indeed.

Shanghai's subway system is wide and extensive, but also confusing and extremely tiring to newcomers. Another constant necessity of riding the Shanghai subway is changing subway lines. The Shanghai subway has 14 lines and over 300 stations, while Bangkok's BTS and MRT systems combined consist of only 3 lines and have just over 50 stations. Changing BTS lines in Bangkok means making a 15-second walk to the other line just on the other side of the train platform. Changing subway lines in Shanghai often means making a 5 to 10-minute walk to a very far away platform. And during this entire walk, there is often not even a foot of space between you and thousands of other people. I mean this literally - there's a sea of people in many of the subway stations. Bottom line: you can get almost anywhere on the subway, but riding the subway sucks big time. So if you can efficiently and cheaply avoid it, I strongly recommend you do.
Conclusion: Shanghai is China's most internationalized city, and it has a noticeable foreigner population (though not to the extent of Bangkok). Being stared at is a regular part of being a Caucasian in China, but the staring is usually less extreme in Shanghai than it can be in other Chinese cities. Shanghai cuisine is mediocre at best, but there's plenty of other good Chinese food to be had for relatively cheap. There's also a decent amount of mid to high priced foreign cuisine around the city. The women of Shanghai are very appealing to the eyes, but they have a very bad reputation as the worst lovers in all of China. Shanghai has a lot of impressive looking skyscrapers, but since the city is still relatively young, it doesn't have all that many interesting tourist sites. The local subway system is extensive and cheap, but it's very unpleasant and often best avoided. If you're a fan of mega cities, you'll probably like Shanghai, if not, then you probably won't like it. Whether or not you would ever want to come to Shanghai totally depends on the type of person you are and what's on your agenda. Shanghai left a fairly positive, though not wonderful, first impression on me. I'm sure I'll be back in the Shang sooner or later.