re: not sleeping properly, I think I had that model of Dell, or it was a problem common to more than one model (in my case, a C640 - overheated its motherboard enough to need a replacement while running on in a bag when it was supposed to be sleeping, although it was on my commute, not a flight.)

I don't use hibernate anymore unless I'm in the middle of critical work; the combination of Windows 7 with SSD shuts down and starts up quicker than the hibernate/restore times.

As for playing by the rules, "sleep" mode is off enough for most purposes; the amount of power and activity to keep memory contents is trivial compared to the fully running system.