There seem to be conflicting ideas between the some people suggesting that action move to Coruscant (something I don't think makes sense).
And a recent suggestion (derived largely from a misunderstood comment I made about on of Angel's mockups) of reviving the early draught idea of having Palpatine arrive on a space faring palace which docks with the Death Star.
As a compromise in my mockup I show the palace leaving Coruscant and then docking with the Death Star.
The tower now becomes a mooring pylon so when Luke goes up in the lift he goes into the gondola under the Palace (the Throne Room is connected to the palace not directly to the tower).
Rather than leave his palace he essentially takes his palace with him, the idea being that he no longer feels the need to mix it with normal people and just hangs out with his pasty faced goons who also die when the Death Star goes bang (making the Rebels victory even more decisive).
The take off (if needed) could happen straight after Vader announces the Emperor is on his way and the arrival would happen in the same place it does in the original version but instead of a normal shuttle the Palace would dock with the mooring pylon and Palpatine would come down in the elevator to inspect the troops and the station.