One company that lets me wait for as long as I want, and then some, is MLB.com. Those blessed souls on average let me listen to anywhere from 7-10 tracks of beautiful muzak.
Another very considerate service that lets me listen to classical music is Brigham Young University's Financial Office. They tell you an approximate wait time, and then (bless them) they extend it by two or three times the approximation.
Now one company that has a very short wait time, hardly ever letting me hear the first track all the way through, is my bank. Chevy Chase is quick, and the lip service and real people on the other end are disconcertingly non-muzak-like.
So, that is my observation today. Feel free to add to the list.