Breasts are one of the most sensitive parts of a woman's body, so a man who knows what to do with them will have no problems keeping his woman happy.
The nipples are the most responsive to touch and you can do a lot by stroking them, gently fondling them or even licking them. Every woman has different levels of sensitivity and you need to gauge it to apply pressure accordingly.
Yes, the breasts are s*xy and sensual, but remember that they ought to be handled with care. You should not go on the attack and pounce on them like they are squeeze-toys.