Amine, I think that you have a very strong academic profile, so one of the top 10 schools will surely offer you something.
Myself, I only applied to the top 3 (for my field). And to say the truth, one month ago I did consider CMU as a "safety school" :-).
At the moment I have the very depressing sensation that no school will accept me.
The other alternative that I have is an excellent place here in Europe, so I did not apply to second-tier schools, or to the top-schools that are not so attractive (es: GeorgiaTech -- great school, but who will survive 5 years in Atlanta???).
In the end, MIT and Caltech did have a higher "expected value" from my point of view, but the *variance* is very big in life.
Now I'm forcing myself to think of the plus side of a PhD here in Europe:
+) 1h plane from/to home for 30 euro
+) 2x the money and 0.5x the stress
+) much more freedom in choosing research topics
But there are many minuses:
-) not so curriculum-building as a MIT PhD
-) much less networking
...