The more I think about the Great Vader's Isolation Chamber Debate™ :) the more I'm liking the idea of an elevator entrance a'la the Emperor's throne room in ROTJ. It isolates the room and doesn't make it implausible that Vader is running all over the ship since we have no idea where the chamber may be located. And it also ties more design elements together between the Star Destroyer and Death Star.

I also like Monroville's idea of decreasing the ambient lighting. Maybe pushing the elevator back a little and having the room dimly lit until Vader's reveal would give it a greater scope, rather than having the chamber so close to the entrance.