It does sound interesting but I would feel left out wanking in the corner. If I was feeling voyeuristic I would rather hire three girls - one to massage me and two others to massage each other next to me.
Pay to sit in the cuck chair and watch one of the male masseuses get a sensual massage. Where's the fun in that?
Or you can pay to have a bisexual doubles massage and have a girl and guy massage you at the same time. Stare into the alluring eyes of some dude as he wanks you off while the female massuess massages your balls. WTF
Doubles footjob... cum on Kimmy and Luna's feet at the same time. Woohoo