I watched a bit of The Empire Strikes Back recently in order to verify a bit of dialogue and find the time stamp for it, and I noticed a detail in the set. Last May, I wrote a post about differences between the original version of the film and the special edition, and one feature I mentioned was these panels in the background of Cloud City:
When Han, Leia, Chewbacca, and C-3PO arrive, these panels have a warm glow behind them. By the time Luke arrives, however, after the Empire's trap has been sprung, this warmth has disappeared, and the panels are colorless:
This contrast in color illustrates the change that has occurred. At first, Cloud City seems like an inviting place, but once the Empire's presence is revealed, it becomes a stark and unwelcoming environment.