I always take a battery-operated travel alarm clock -- just in case. Also, the alarm on the cell phone is also a great option.

With the hotel alarm clock, I get creative if I can't figure out how to change the alarm clock. If it is 12 hours off, then set your alarm for 12 hours off of the time you want to get up. For example, 6pm instead of 6am, etc, or just ask the front desk how to set it.