Husband here; For me as a bi-hubby is it great to have a tolerant lover for my wife. It is great when I am allowed to put my tongue on your dick while you fuck my wife. Or when I lick your asshole. But really great is the feeling to have your balls in my mouth and feel when your semen left your balls and are ready for my wifes pussy.
My wife's favorite thing is for me to lick her clit while she is being fucked. There really is no way to do that without licking the bull's cock and bulls with all the movement going on. From time to time, his cock may end up in your mouth. Tasting her juices on his cock really puts you in your place. Then when he cums, it tis going to drain into your mouth.