The pinnacle of Evil Planets is Dromund Kaas. In the old EU when Korriban was the sight of a clone wars battle(meaning that it was pretty well known) Yoda made efforts to dismiss the mere existence of DK as a rumor. It turned Kyle Katarn to the dark side simply by being the planet he was on. I would love to see Dromund Kaas in the ST. And Nar Shaddaa. Can't stress it enough, Nar Shaddaa is awesome.