one of the problems with big tits is that they have the same number of nerve endings as small tits but spread out over a larger area, so basically they're less senstive. most women won't admit this, though. as soon as it's brought up they're all "not me, my tits are the glorious golden entryway to my tingling clitoris and ejaculation!" that's really annoying.
sometimes, probably due to hormones, my tits get really sensitive. most times, though, they're stictly for my husband's enjoyment, 'cause i don't get much out it except that he's all happy and excited and has somethingto jizz on.