We experience it every once and a while. It's not necesarry for either of us to be blown away with pleasure, but it does add something to the emotional/intimacy side of sex/lovemaking. I always feel closer to my gf when I am able to cum at the same time as my she does, although she usually has multiple orgasms before I have one.
For us it's about good foreplay, and my husband's control--he holds on and doesn't cum until I do. Sometimes he pulls out and takes a little break for 30 seconds or a minute to avoid cumming before me, if necessary. We cum at the same time more often than not, and we always do if it hasn't been more than a day or two since we last had sex. Before him, I had no idea this could happen. I think it's really special and wonderful!!
Never with a boy, but many times with women. Of course, that's partly because I never learned how to have a G-spot orgasm until I started having sex with women...makes it a lot easier when you either have fingers inside you that can curl and point just where you want them, or can choose any dildo you want!
I get off pretty easily. Normally a few times a session. My biggest and best orgasm, though, is when he gets off. I love knowing that I brought him pleasure.
Then again I get off when I give oral sex too for the same reason.