American's find breasts facinating. Not one person (male or female, gay or straight) can honestly say that if some woman walks by with nice full breasts and cleavage (not huge...perhaps a full C) that they don't notice. I notice. I'm not gay. I just think that breasts are beautiful. They are a sign of feminity. I love my boobs!
And we like cleavage. It is attractive. They have actually done studies on this. That is why the Wonderbra market is so huge. (no pun intended!)