My overnight bus ride from Santiago down to Madrid was pretty interesting! I've never ridden a bus long-distance, and was lucky enough to somehow wind up in a front row seat, with no one sitting beside me, so I could sort of stretch out. Most of the rest of the bus was filled with a bunch of Spanish teenagers, and there was a movie playing during the first part of the trip. The movie had to have been R-rated, and involved some very explicit sex scenes throughout, but no one seemed to mind, and the youngsters didn't really seem all that interested in it.
We pulled over in the middle of nowhere after awhile, and another bus driver came walking up out of the darkness to relieve the first driver, who also disappeared into the night. At the beginning of the trip, I looked toward the back of the bus and didn't see any kind of restroom, so I just figured it was a hold-it-until-you-get-there affair. Then, we stopped at some motel/restaurant or something for a 15-minute break, and we did this two or three more times along the way.
It wasn't a bad trip at all, and we arrived at the downtown Madrid bus station early in the morning, then transferred to another bus that took people to the airport ...