This summer’s biggest Broadway success story wasn’t some cutting-edge musical featuring agressive tap-dancers, and it wasn’t a provocatively-titled, fast-paced romp from the mind of one of theater’s hot new stars. No, the king of Broadway this summer was none other than the late Eugene O’Neill, whose four-hour play, Long Day’s Journey Into Night, has garnered rave reviews and standing-room-only attendance in its 5-month run. Some of the success of the revival can be chalked up to star power and savvy marketing that pandered to the ‘serious’ theatregoer. But some see it as a sign that Broadway crowds are ready to be challenged.