I've always found the inclusion of a personal pronoun in an imperative very unnatural. I agree entirely that sentences like "Oh, just go to bed, would you?" or "Go to bed, would you?!" are fine but "You go to bed" is clunky.
"You go there right now" sounds awkward to me. If it were "You! Go! Right now!", it would be a natural imperative. "You!" would simply be used to get the attention of the person being addressed.
I think we've seen from various posts in this thread (and others) that most of us would not use a question tag with an imperative (much as I hate to disagree with Swan!)