The common failures are:

Blind (if fitted) - ensure it goes up and down with no bad noises.
Seat Heaters - ensure they all work (Elites have rear seat heaters, other dont) - should be warm to touch within 2 or 3 mins.
Dash warning lights - ensure that ABS/Airbag/Engine lights all come off with ignition and go out shortly after (engine one go out when started)
Radio - ensure it works, and that CD changer works (radio model 2006 in particular seems to suffer from naff CD changer units)
Central Door locking - ensure all work, and in particular, you car open drivers door after locking.

Thats only common electrical niggles I can think of.  All but the seat heaters are easish fix anyway, using second hand parts...