ad - the main reason for me was i applied literally at the last moment before the deadlines. i had just wrote my gmat then and did well enough that i wanted to try to see if i could get into a program for Sept. 2009. however, after i got in, i reconsidered my situation, and though i'd have a better chance of getting into other european or north american programs.
here's also a bit of info/advice that you won't get elsewhere. since my dad went to Tsinghua for undergrad, he knows and also was classmates with several of the current senior administration at the school. after talking to them for career advice, the general feedback i got was this - although Tsinghua is a great brand name in China right now, the Chinese corporate culture still favors outsiders with western degrees. it doesn't even have to be that elite, but as long as it's a western degree from a respectable program (think near elite schools or better).
also, without making this into a racial thing, race does matter and it factored heavily into my decision. if you're ethnically asian (like me), then a western mba will be held in higher regard than a Tsinghua mba. this is mostly because you'll be considered as having "made it" in the west before returning to work in china. whereas if you had a Tsinghua degree, you'll be considered as someone who hasn't made it in the west and had to come back to study in China. although you got your degree from the best Chinese institution, it still has the stigma of "made in China".
however, if you're of caucasian descent or anything non-east asian, i'd say a Tsinghua degree, combined with a couple of yrs in Beijing to get accustomed to the culture and language, will be very beneficial because you'll be seen as a foreigner with a genuine interest in China - you've come to study in China and you've come to study at the best institution here, i.e. Tsinghua. that's a story that you can sell to recruiters and hiring companies after graduation in a good light, and it's a better angle than to just be another foreigner with no respect or regard for the Chinese culture, who got his degree from an elite school in the US and came to China looking to exploit the local business opportunities. see how that fine distinction can be spun in different lights? true, it's not the same as a Harvard degree - but when you're competing for a job with someone from the west, you'll have a much better vibe with the Chinese. when you're trying to close a business deal, you'll be able to impress them with your cultural and linguistic skills that other "fresh off the boat" westerners won't have. basically, you'll be able to endear yourself to the Chinese, and that'll pay huge dividends in your career.
anyways, that's mostly why for me, it made sense to wait it out a yr and apply for a bunch of north american and european programs that to jump straight into bed with Tsinghua. the cautionary note here (aside from the race thing) is - i'm Chinese and already have some sort of family connections and networking in China, so i can afford to attend an mba program elsewhere, and then go work in China because the doors will already be open for me. for someone without that network, it might be more valuable for them to attend Tsinghua or CEIBS to gain the contacts and cultural experience if they're interested in working locally in China afterwards.
ps - on a side note, i strongly believe in Tsinghua > CEIBS in the coming years, as the CEIBS program is rather one dimensional and tailored for mid management professionals already working in China, whereas Tsinghua is more academically rigorous and will have both a stronger faculty and better recruiting once it becomes more established and better leverages its undergrad reputation.