I hate to be that one guy who makes a critique after all this praise you're getting, but one thing you may want to watch out for in future background drawings is not having lines too close to each other (I'm sorry if I can't remember what my college professors called this). Basically, in this case, to make it more obvious that the chair bottom is closer to us than the book case in perspective, it would help if the chair bottom extends past the bookcase. It looks like the vertical line on the chair almost perfectly touches the vertical edge of the book case, and I guess it makes it look like the chair bottom is flat?
Man, I need to look up that term my professors used so I don't have to explain this in so many words. Either way, this drawing is very entertaining and great overall, I just wanted to help a little bit to make future stuff look even better!