For KL I found that it would be easy and not too expensive to just go to town and get to my hostel (and the ratings for sleeping in the airport there were not good). For Shanghai, since I was actually arriving in Hangzhou (about one hour by train or two hours by bus away from Shanghai center) with the late arrival it would be easier to just stay in the airport. Since the airport was new, there were no reviews, but I decided to chance it. I ended up finding a great spot- padded bench seats with no armrests, quiet, no people and with a power outlet close by. I watched a movie and then put on my face mask and went to sleep for about 5 hours. In the morning I found my way to the train and (after going to the wrong address once) checked in at the hotel where I would meet the students from Denver that would arrive later that night.
I spent a little bit of time adding my reviews to sleepinginairports.net for some of the airports I've been stuck in including Iceland, Amsterdam and Tirana. The website is great for those of us lucky enough to fly standby, but not lucky enough to make it out on the first try. My mom wished she had know about the site before they came to see me- it might have made their overnight in Seoul a bit more comfortable. This time in China was the first time I had chosen to sleep in the airport instead of just getting stuck there, but now with this site, I might be sleeping in airports on purpose more often.