I'm prone to minimalist backgrounds, so it doesn't distract from the joke or body language, or clutter the panels, which is more of a danger when you're working with black and white as opposed to colors. I actually removed a door in the background of a future comic because it was too intrusive. I like little things that just suggest the setting, like the bit of flaming bus wreckage in panel one. It's much subtler. Plus, less work for me, so there's some pointers right there.