Often people wanting to know if Ubuntu will run on a potential hardware purchase are advised to use the LiveCD, perhaps in-store, to check hardware compatibility. For example, this answer suggests drivers will usually not be an issue if they work off the LiveCD, but it also says to test "extensively".

Given that if you do this in-store, you'll have a limited time period to do the testing, what is the most efficient way to test the computer? For example, after running a program like vlc to check video and audio...is it then necessary to try a music player too? What settings should be checked?

Let's assume I am interested in all the usual laptop functions (suspend, hibernate, wireless), in addition to things like built-in webcam, microphone, etc.

Also, if the laptop doesn't have an optical drive (like some of the newer thin laptops), then I would have to boot from USB. Is this just as reliable as testing from the CD? (I feel silly asking this, but I know some laptops behave differently booting from USB, e.g. Apple)