has anyone ever had a session where they paid the girl to cuckold them with their S/O with a strapon or just have their S/O worship the sessionette? 

Mistress red diamond does them

Mistress red diamond does them

any experience with them you can share?

Has anyone ever had the bodybuilder play with their wife/gf?

My ex-wife was a Olympic weightlifter/powerlifter who would do strong woman events.  I brought her with me to a couple of sessions with some bodybuilders and we also played occasionally with some of her strong woman athlete friends who were national and world ranked. 

Wow DCReviews you were living the dream. I'd expect powerlifter/strongwoman types to be stronger than most fbbs though, so I'm wondering who was admiring whose body the most when she met your fbb session providers, lol.
She could have intervened to rescue you, but if you were married to a woman like that, I take it you're probably quite a big man too?

I do have a fantasy about me and a woman I'm sort of with (maybe a first or second date) having some sort of encounter with a bodybuilder. A really swole deep voiced fbb who's not off season but not overly shredded either and overpowers us both before having her way with us.
It couldn't be a serious partner though, as our relationship wouldn't survive seeing me swoon over a woman's muscles and get carried submissively in her strong arms. She'd never look at me as a man again!

 LOLOL. Maybe you have to date someone who is a little bit more open minded and bisexual, there are girls out there who enjoy the female bodybuilder physique as well. Or just females in general.  Bringing up something like that earlier in your dates would let you know how open someone is.

I have dated a bi girl briefly and she was very much of the opinion that men should be men and women should be women, and she got something very different out of both sexes.
She preferred men though, and I'd possibly expect more lesbian-oriented bis to to be a bit more boundary pushing.

I also once dated a (straight) woman who proved a bit stronger than me when we wrestled, but she didn't like realising she had the physical upper hand, or that it turned me on.

There are plenty of sporty women who like showing off that they're stronger than some guys, but it's rare they'll go for one of the weak ones. They'd still rather be with a man whose muscles they admire, with whom they can be the weak girly one.
Unless you're lucky enough to meet a strongwoman powerlifter with like minded friends who're happy to play with you as the designated beta of the group, lol.

In terms of verbal domination you definitely can find a wider variety of females to engage in that fetish. And believe it or not many of these session girls are willing to play with couples. You have to find the right one with the right chemistry.