I find when getting fucked that it doesn't hit my prostate as much as when I'm getting some finger play...I think it's because a dick goes well past and you start a whole other set of sensations going. Though when I'm getting fucked "missionary", I like to have my partner pull almost completely out so the curve of his cock drives his glans into my prostate on the way in. If he's real good, he can ride that sweet spot just right and get my juices shooting without so much as touching my junk!