I'll chime in!
I voted 'never,' even though I did with at least one of my old boyfriends (every once in a while; it wasn't a regular thing). I did it a bit when DH and I were dating and engaged. Maybe a bit when we were first married, I can't remember. But somewhere around getting pregnant and having our two kids, I have absolutely no interest in doing it anymore, and I haven't wanted him doing it to me, either.
It just grosses me out now, even more than it used to (both being the giver and the receiver). Honestly, I'm almost never in the mood to DTD, whether it's oral or otherwise, so I would have to be *insanely* horny to want to give another BJ. Sad for DH, I guess, if he cares (which he either doesn't or just doesn't admit), but it's not like he's been doing anything romantic the past 5 years to get me in the mood for sex, anyhow.
Back in the days I would do it, it was when I was *really* attracted to the guy (like hot & heavy into him and still found him super attractive). Part of why I did it is because I didn't have to worry about getting pregnant from it.
Sorry for the brutal honesty, but it's just my take on it.