Ooh! Backgrounds are not my favorite thing to draw, but usually I do include them.
Depends on the scene - if it's a big panel, I'll want to include the background in a more detailed way. In "regular" panels, I'll put a background, but more loosely defined so that the focus is on the characters. Sometimes, if the background has already been established, I might just use solid colors as the background.
I also play around with angles sometimes, as if my comic was a movie storyboard! I especially like doing this in "boring" scenes when the setting doesn't change.