I guess he could be staying there because it is kind of in effect the birthplace of Darth Vader in a lot of ways. Could be some Sith thing too to have to face your pain and whatever.
I did like the Vader scene though, not going to lie I was grinning ear to ear like the Joker all through out it. It was bad ass. I'm glad it's in the movie.
It made up for "wussy Anakin" in the prequels. The castle design is from Ralph McQuarrie, it was actually I think supposed to be the Emperor's throne room in ROTJ, but they moved that onto the Death Star.
I liked the Vader scene at the end, when he's tearing shit up :)
I think the filmmakers had some issues finding a healthy middle ground between homage and winking at the camera. I have to say I cringed at Vader's pun and at the Evazan/Ponda Baba cameo. R2 and 3PO seemed a little forced too. Seemed like Edwards was pausing for applause whenever a familiar face popped up.