Turn your alarm (iPhone) up to max and make sure it is an obnoxious tone. Before Apple took away the ability to record and use any sound, I used a recording of the sea lions barking on the piers in San Francisco as my alarm ringtone. It cuts through the earplugs...

In any case, most hotel phone ringers or cellphone alarm ringtones will wake you up - your body is primed to alert to it. The foamies blank out all the extraneous noises that keep you up - vacuum cleaners, maids habla-ing in the hallway, etc.