Area 51

its a possibility

I hope not. The Area 51 gimmick has become overused and a little dated. The level of conspiracies going on in the new film are of such great magnitude that intigrating something as suspect as Area 51 comes off fairly cliche.

That was my thought as well. I think the mutos are hidden under the earth in Area 51, if you look at the foot that stomps down, it's glowing. This is common in things that live in areas without light (deep in the ocean for example). So, mutos living in underground caverns that we access in Area 51 fits.

Everyone knows area 51 is where Elvis and Michael Jackson play golf. 

This makes more and more sense the more I think about it. Aside from the fact that a good portion of the movie seems to take place in Las Vegas, there's also the fact that the nuclear tests in the Pacific were attempts to kill Godzilla in the films fictional history. There was also a lot of nuclear testing in the Nevada desert... perhaps those were attempts to kill some other powerful monster(s)? Of course, this doen't make Area 51 itself likely to be the major M.U.T.O. research facility; it's just as likely that it will be some other random base, or maybe there will even be multiple different facilities with entrances to the cave sytem the monsters call home. I'm fairly convinced now, though, that the film will have Godzilla emerging from the Pacific while the "Mutos" emerge from sinkholes in the Nevada desert.

Double post, sorry.

You got a interesting point there @LINKZILLA. That makes sense given that in the trailer, Las Vegas had been attacked. Mutos could have escaped and caused havoc. But what I still don't understand in that theory is how Godzilla and the Mutos met if they are so far away.

Maybe the military somehow lures the creatures to a common point to battle. It seems that in the 2 trailers, the military are using red flares to get Godzilla's attention, so maybe that is part of it.