Anything $50 and up is fair with light touching for 90 minutes. $60 is more appropriate cuz usual standard tipping is $40 for 60 min with minimal touching. If you got their pants down, $80-90 is fair depending on how you play. I usually tip more if I enjoy the session.
Anybody who tips less than $50 for a 90 min session with HJ is a cheap bastard, especially those with insurance coverage.
We had one guy last night tipped a girl only $40 for a 90 min session with 2 HJ even tho' they had agreed upon for more tips. I felt bad for the girl and chipped in 20 bucks extra out of my pocket to make the girl feel better for the rest of the day and to keep her in good mood. She is the sweetest girl there and not a tip hungry one with 90% repeat customers. I will tell her when she is in good mood and see where will that lead to on his next visit.