What ever happened to opening the door and asking them to keep it down? If they want to be idiots and disregard the request (at 2am), then it might be the time to cal the front desk etc.....

I used to get really mad and set the alarm clock, volume - max, for 5 minutes after I leave the room (usually at 4am) and other reactive type behavior.

Although I've found that with a little proactive polite and tactful interdiction I could get an apology and have them stop the annoying behavior.