I highly recommend Mystery Adventures!!!
I was part of Tanya T.'s bachelorette group and she really breaks it down. Which makes it a little hard to review because i don't know what else to add.
I've had many trips to vegas doing the typical vegas acitivities (shows, club, gamble, etc) but this topped them all. The staff was wonderful and really got into character. Like Tanya T. said they change the plot every year right around labor day. So maybe we can make this an annual festivity :o)