I love my "couple year old" ThinkPad. Relating to suspend, the only problem I have is that there seems to be some kind of window. If I close the lid and then remove the power within a couple of seconds, suspend fails and the machine continues to run in my backpack. If I unplug the power first, then close the lid, it suspends properly.

I have a couple thoughts on how to debug it, but honestly... I haven't had the inclination to invest that much time in it, and the "unplug-then-close" habit has become so ingrained that I'm only burned by this about once every other month or so now.