If I am able to secure a multiple entry Visa from the Chinese Embassy, would I be able to do the following:

1. Enter China
2. 30 days later enter Hong Kong for 1-3 days (no visa needed if stay under 90 days)
3. Re-enter China (and have 30 more days)
4. 30 days later enter Korea (no visa needed if stay is under 30 days and proof of transportation out shown) and stay 1-3 days
5. Re-enter China (and have 30 more days)
6. Then fly out of China back home to the US.

My goal is to stay in China for around 90 days without having to ask for a "90 day visa" which I hear is not easy to do.

It appears that you are a US citizen, so yes, it can be difficult (but not impossible) to get an waiver for the 30 day limitation. With a group, it will not be difficult at all, but it's a different story if if you traveling independently.

You can definitely do the itinerary you suggested, providing:

(1) the visa granted is over 90 days (The tourist 'L' visa granted for Americans is generally now 1 year in validity, so this should be fine). The clock starts ticking from the date of issue, so make sure you don't apply too far in advance.

(2)Pay close attention to the dates of exit exit/entry, if you are over 30 days on any stake, you will incur fines (around $60/day, if I remeber correctly)and put the validity of the visa at stake.

Lastly, although not strictly necessary in practice, to avoid the possibility of any difficulties at immigration, I'd advise that you have your return plane ticket to the US before you arrive in China.

I am reading a thread on another forum that someone just get a one-year multiple entry visa that says each stay can be up to 120 days.

Your mileage may vary, or course.

The durations are country specific.
The Chinese made this restriction against Americans in response to the outrage around US fingerprinting foreigners at immigration points.

I got a new one year visa in august and it had the 30 day restriction.

Are these durations specific to WHERE I get my visa, or always because of nationality?

For example, could I get a longer duration visa easier from Hong Kong or Japan? Or will I always have the same restriction being American no matter where I get the Visa from?

I recently acquired a one year, multi entry "L" visa, with duration of stay limited to 60 days. This was as of October 1, 2007 and since i live in los angeles, it was easy to drive to the consulate. I requested a 90 day stay, but the consulate was not granting that length of stay, at that time. The cost was $100 and was the same for a one entry, double entry or multi entry tourist visa. In the past, when i visited China and wished to stay longer than my 60 days, i travelled to Hong Kong and easily acquired a new 30 day tourist visa (I was staying in Shenzhen, at the time). Good luck !

So your "L" Visa has a duration of 60 days TOTAL or is it 60 days for each entry? For example, can you stay 60 days, go to Hong Kong, and re-enter China (without appling for anything more) for another 60 days.

This is how I assumed "double entry" and "multiple entry" Visas worked. EACH stay was limited by the days allowed (normally 30 days, or 60/90 like yours).

(or... you have 60 days to stay in China all together... no matter how many times you leave and re-enter?)

I contacted a third party visa service who told me that with a multi entry visa, you can exit mainland China and when you return you can stay for the length of your issued visa. So, if you have a 60 day multi entry visa and you leave mainland China and spend the day in Hong Kong or spend a few days in South Korea , when you return to mainland China you will have an additional 60 days to stay in mainland China. Good luck.