in reference to the requests for Star destroyers over Cloud city, sure Vader might be a vengeful bastard with anger issues, but if the Empire can gain control of a mining facility that produces Tibana Gas without having to resort to excessive force, why wouldn't they? and if it's deserted , more the better they can bring their own people and man the facility themselves, regardless of how the events with Luke etc panned out i'm sure the Empire, I'm sure the Empire had their sites on securing Cloud city for themselves.
it might be visually impressive, but I'm sure it suits the Empire far better if they just let everyone but the rebels escape.