I think I'd call it Dance-Off. Only $29 a month, no contract or sign up fee.
I was also thinking that this gym would have Wiis & Kinects all over and you could just play those too. But no just sitting there. If Just Dance is on, you have to get up and move. If you're playing tennis, you have to get up and play. If you're playing Rock Band, you have to rock out as if you're really on tour. Boxing is always up & ready to go. How fun would this gym be!