One thing you can do for variety is simple dances as no-walkthroughs. Line 'em up and getting them dancing. Even when they say they want advanced dances, they still want the joy of successfully dancing to music.
It's easier to write a challenging dance than it is to write a good simple dance; and I've written many challenging dances. If you're looking for variety, a 6 facing 6 might be up your alley:
"2 out of 3 ain't bad" is the only one I've actually run with dancers
There are loads more complex ones on my site (anyone remember the Greenfield formation contest?), but I'd stick to the ones that have been field tested.
I hope you have a tight group of dancers to practice on before hand; as these types of dances benefit even more from testing and discussion in small groups so you can pick apart where the trouble spots lie. It's hard to get enough folks though to test larger formations, or end effects.
Have fun.