In the U.S. "Bless you" is common. When "God bless you" is used, it is said quickly, almost as a single word, g'BLESHu.
In my experience (Northeastern US) "Gesundheit!" is actually QUITE common. That is probably regional, and it is probably from Yiddish rather than German.
It is, incidentally, a tradition that goes back to the 1300s, because a sudden sneeze was often the very first symptom of bubonic plague.