One of the ideas I am playing around with to utilize a larger than usual chorus for this show is to divide some of the background vocalists/dancers up into specific roles and functions. A concept that intrigues me is that Dr. Frank-N-Furter has a trio of girls who follow him around (or just suddenly appear) when he sings. Every time he has a solo, there is always a funky soul/R&B harmony in the background, so what if there were some alien girls who sang those parts specifically (backed up by the rest of the cast when necessary)?
Obviously, there is definite inspiration from the Judas trio in the film version of Jesus Christ Superstar (pictured above, video below). I especially love the white/silver/glitter afros on them.
Other inspirations for this would be the girl trios in Little Shop of Horrors, Hairspray, and Caroline, or Change.
Vern and I were discussing this briefly last week, and I also would LOVE to play with the idea of one of these characters being a male actor in drag who can sing falsetto and hold his own with the girls, to play with the gender-bending aspects of the show. I'm definitely influenced here by the character of Unique from Glee (videos below).