If I may, I'd also like to add some suggestions that might make your list. The first being a scene from the amazing spiderman (I believe near the end of chapter 13) where the lizardman encounters a swat team, it has decent length, depth, and amplitude from what I could perceive.
Actually two more scenes just from the first amazing spiderman, when he first gets his powers and is sleeping on a train (very strong frequency sweeps). Also the ending scene where he slingshots himself from a crane arm (just for the depth, seems even stronger than the dragon crash in httyd).
Also the first dragon fire scene from beowulf is pretty intense.
The hitchhiker's guide to the galaxy also has a nice extended bass scene when the vogon ships first arrive to earth (their low frequency droning lasts for a while).
And though perhaps not as long or as deep, near the ending of cloverfield when the monster fully reveals itself has some pretty high amplitude bass (though the alley encounter scene might definitely prove to be a more worthy choice).
Forgive me for the spastic nature of this post, your work is wonderful and these scenes are merely suggestions.